TET-1465 Add `gen_ai.embeddings.input` to sentry-conventions

Instructions and example for changelog

Please add an entry to CHANGELOG.md to the "Unreleased" section. Make sure the entry includes this PR's number.

Example:

## Unreleased

### Features

- add gen_ai.embeddings.input as attribute ([#195](https://github.com/getsentry/sentry-conventions/pull/195))

If none of the above apply, you can opt out of this check by adding #skip-changelog to the PR description or adding a skip-changelog label.

Generated by 🚫 dangerJS against 0853a58

You can scaffold new attributes, so all required files are generated/updated as outlined on https://github.com/getsentry/sentry-conventions/blob/main/CONTRIBUTING.md#usage.

@cleptric I've re-created the attribute with the scaffolding tool

@constantinius Please run yarn generate && yarn format as described in the pull request template, we shouldn't get such a large diff. That should probably get rid of the merge conflicts as well.

@lcian Sorry, missed that. Did now run it and yes, the merge conflicts are gone