Add cargo semver-checks as a step in the patch release process (rer…

…un-io#5186)

[`cargo
semver-checks`](https://github.com/obi1kenobi/cargo-semver-checks) will
check that we haven't introduced any semver breaking changes

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/5186/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/5186/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/5186/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/5186)
- [Docs
preview](https://rerun.io/preview/10d8b8604c333395c2dd8dd6569276377442d37f/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/10d8b8604c333395c2dd8dd6569276377442d37f/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

RELEASES.md

@@ -57,6 +57,8 @@ Note: you do not need to create a PR for this branch -- the release workflow wil
 
 3. ### If this is a patch release, cherry-pick commits for inclusion in the release into the branch.
 
+  When done, run [`cargo semver-checks`](https://github.com/obi1kenobi/cargo-semver-checks) to check that we haven't introduced any semver breaking changes.
+
 4. ### Update [`CHANGELOG.md`](/CHANGELOG.md).
 
     It should include: