Bump boto3 from 1.36.16 to 1.36.21 in /packaging/release (#5903)

Bumps [boto3](https://github.com/boto/boto3) from 1.36.16 to 1.36.21.
- [Release notes](https://github.com/boto/boto3/releases)
- [Commits](boto/boto3@1.36.16...1.36.21)

---
updated-dependencies:
- dependency-name: boto3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

packaging/release/requirements.txt

@@ -1,4 +1,4 @@
 PyGithub==2.6.0
-boto3==1.36.16
+boto3==1.36.21
 docker==7.1.0
 requests==2.32.3