build(deps): bump pygithub in /.github/actions/pr_notifier

Bumps [pygithub](https://github.com/pygithub/pygithub) from 1.55 to 1.56.
- [Release notes](https://github.com/pygithub/pygithub/releases)
- [Changelog](https://github.com/PyGithub/PyGithub/blob/master/doc/changes.rst)
- [Commits](PyGithub/PyGithub@v1.55...v1.56)

---
updated-dependencies:
- dependency-name: pygithub
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/actions/pr_notifier/requirements.txt

@@ -75,9 +75,9 @@ pycparser==2.20 \
     --hash=sha256:2d475327684562c3a96cc71adf7dc8c4f0565175cf86b6d7a404ff4c771f15f0 \
     --hash=sha256:7582ad22678f0fcd81102833f60ef8d0e57288b6b5fb00323d101be910e35705
     # via cffi
-pygithub==1.55 \
-    --hash=sha256:1bbfff9372047ff3f21d5cd8e07720f3dbfdaf6462fcaed9d815f528f1ba7283 \
-    --hash=sha256:2caf0054ea079b71e539741ae56c5a95e073b81fa472ce222e81667381b9601b
+pygithub==1.56 \
+    --hash=sha256:80c6d85cf0f9418ffeb840fd105840af694c4f17e102970badbaf678251f2a01 \
+    --hash=sha256:d15f13d82165306da8a68aefc0f848a6f6432d5febbff13b60a94758ce3ef8b5
     # via -r requirements.in
 pyjwt==2.1.0 \
     --hash=sha256:934d73fbba91b0483d3857d1aff50e96b2a892384ee2c17417ed3203f173fca1 \