Adds a Github Action step to run benchmarks in CI and report on the differences with `main`.

It uses a combination of [gobenchdata](https://github.com/bobheadxi/gobenchdata), the [netlify/delta-action](https://github.com/netlify/delta-action) and a simple Go script to glue them together.

Example from lower down in this PR:
![Screenshot 2022-11-22 at 18 56 21](https://user-images.githubusercontent.com/1121616/203398189-b8a0b94c-bb1b-416d-94d4-84cf71feb176.png)

Closes #424

We need slightly elevated permissions to make a comment when the PR
comes from a fork, and I believe this should do the trick.

Github Actions security when it comes to external PRs is a bit of a
minefield, but because we're avoiding the `pull_request_target` trigger
here, and not running any repository code in the delta-action itself, I
believe this is safe.

This should fix the issue we're seeing here
#430

The fix in #436 didn't
work; looks like you can't use the GH bot token from a forked repo PR
either.

…n option (#431)

🤖 I have created a release *beep* *boop*
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##
[1.8.2](v1.8.1...v1.8.2)
(2022-11-25)


### Bug Fixes

* **test:** Values check test should account for `IgnoreInTests` column
option ([#431](#431))
([ffffcd5](ffffcd5))

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