chore(deps): update python-semantic-release requirement from ==9.20.* to ==9.21.* (#174)

chore(deps): update python-semantic-release requirement

Updates the requirements on [python-semantic-release](https://github.com/python-semantic-release/python-semantic-release) to permit the latest version.
- [Release notes](https://github.com/python-semantic-release/python-semantic-release/releases)
- [Changelog](https://github.com/python-semantic-release/python-semantic-release/blob/master/CHANGELOG.rst)
- [Commits](python-semantic-release/python-semantic-release@v9.20...v9.21)

---
updated-dependencies:
- dependency-name: python-semantic-release
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements-release.txt

@@ -1 +1 @@
-python-semantic-release == 9.20.*
+python-semantic-release == 9.21.*