followup of #2118

`pgrx::hooks` is deprecated since 0.12.1 (Aug 22, 2024). We have now
discovered a new unsoundness in it recently. It's time to delete
`pgrx::hooks` now.

Welcome to pgrx v0.16.0.

This release contains support for Postgres 18beta2 and has some breaking
changes in that support for pgrx' "hooks" implementation, which has been
deprecated for over a year, has finally been removed.

Additionally, due to unsoundness issues, direct support for using
`heapless` in shared memory has been removed. Users can still do this
themselves, which requires them to assert they're taking responsibility
of possible unsoundness issues.

As always, first install the latest `cargo-pgrx` with:

```shell
$ cargo install cargo-pgrx --version 0.16.0 --locked
```

Then you're free to run `cargo pgrx upgrade` in the root of all your
extension crates.

To pickup pg18beta2 support you'll also want to run `cargo pgrx init` so
that it can be downloaded and compiled.

# What's Changed

## Breaking Changes

* delete `pgrx::hooks` by @usamoi in
#2120
* improve shmem api by @usamoi in
#2107


## New Features

* update to Postgres v18beta2 by @usamoi in
#2111
* feat: `BackgroundWorker::connect_worker_to_spi_by_oid` by @if0ne in
#2116
* teach `#[pg_cast]` to support 3-argument CAST functions by
@eeeebbbbrrrr in #2119
* teach `#[pg_extern]` about a SUPPORT function by @eeeebbbbrrrr in
#2121

## Bug Fixes

* fix name_data_to_str by @usamoi in
#2108
* add pg_guard_ffi_boundary to direct_pg_extern_function_call_as_datum
by @usamoi in #2118

## `cargo-pgrx` Improvements

* add `--valgrind` to more cargo-pgrx subcommands by @usamoi in
#2109
* `cargo pgrx regress --resetdb` will run `setup.sql` by @ccleve in
#2113


## Code Cleanup

* filter out unrecognized attributes in PostgresGucEnum by @usamoi in
#2102
* Elide needless lifetime by @nyurik in
#2097

## Package/Build System Cleanup

* chore: include pgrx-version-updater into workspace by @nyurik in
#2101
* chore: consolidate package settings in workspace by @nyurik in
#2100
* chore: prepare for 2024 edition by @nyurik in
#2103

# Thanks!  

Thanks to all contributors -- y'alls work helps keep pgrx moving
forward.

**Full Changelog**:
v0.15.0...v0.16.0

…gcentralfoundation#2118)

Theoretically, this results in undefined behavior when an error occurs,
but in practice, it only leads to resource leaks.

This bug is caught through `#[deny(ffi_unwind_calls)]`. During this
process, I found that the `pgrx::hooks` also lack proper
`pg_guard_ffi_boundary`. However, since they are already deprecated, we
should remove them instead of fixing them.

followup of pgcentralfoundation#2118

`pgrx::hooks` is deprecated since 0.12.1 (Aug 22, 2024). We have now
discovered a new unsoundness in it recently. It's time to delete
`pgrx::hooks` now.

Welcome to pgrx v0.16.0.

This release contains support for Postgres 18beta2 and has some breaking
changes in that support for pgrx' "hooks" implementation, which has been
deprecated for over a year, has finally been removed.

Additionally, due to unsoundness issues, direct support for using
`heapless` in shared memory has been removed. Users can still do this
themselves, which requires them to assert they're taking responsibility
of possible unsoundness issues.

As always, first install the latest `cargo-pgrx` with:

```shell
$ cargo install cargo-pgrx --version 0.16.0 --locked
```

Then you're free to run `cargo pgrx upgrade` in the root of all your
extension crates.

To pickup pg18beta2 support you'll also want to run `cargo pgrx init` so
that it can be downloaded and compiled.

# What's Changed

## Breaking Changes

* delete `pgrx::hooks` by @usamoi in
pgcentralfoundation#2120
* improve shmem api by @usamoi in
pgcentralfoundation#2107


## New Features

* update to Postgres v18beta2 by @usamoi in
pgcentralfoundation#2111
* feat: `BackgroundWorker::connect_worker_to_spi_by_oid` by @if0ne in
pgcentralfoundation#2116
* teach `#[pg_cast]` to support 3-argument CAST functions by
@eeeebbbbrrrr in pgcentralfoundation#2119
* teach `#[pg_extern]` about a SUPPORT function by @eeeebbbbrrrr in
pgcentralfoundation#2121

## Bug Fixes

* fix name_data_to_str by @usamoi in
pgcentralfoundation#2108
* add pg_guard_ffi_boundary to direct_pg_extern_function_call_as_datum
by @usamoi in pgcentralfoundation#2118

## `cargo-pgrx` Improvements

* add `--valgrind` to more cargo-pgrx subcommands by @usamoi in
pgcentralfoundation#2109
* `cargo pgrx regress --resetdb` will run `setup.sql` by @ccleve in
pgcentralfoundation#2113


## Code Cleanup

* filter out unrecognized attributes in PostgresGucEnum by @usamoi in
pgcentralfoundation#2102
* Elide needless lifetime by @nyurik in
pgcentralfoundation#2097

## Package/Build System Cleanup

* chore: include pgrx-version-updater into workspace by @nyurik in
pgcentralfoundation#2101
* chore: consolidate package settings in workspace by @nyurik in
pgcentralfoundation#2100
* chore: prepare for 2024 edition by @nyurik in
pgcentralfoundation#2103

# Thanks!  

Thanks to all contributors -- y'alls work helps keep pgrx moving
forward.

**Full Changelog**:
pgcentralfoundation/pgrx@v0.15.0...v0.16.0