build(deps): bump slack-sdk in /.github/actions/pr_notifier

Bumps [slack-sdk](https://github.com/slackapi/python-slack-sdk) from 3.21.3 to 3.26.0.
- [Release notes](https://github.com/slackapi/python-slack-sdk/releases)
- [Changelog](https://github.com/slackapi/python-slack-sdk/blob/main/docs-v2/changelog.html)
- [Commits](slackapi/python-slack-sdk@v3.21.3...v3.26.0)

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

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

.github/actions/pr_notifier/requirements.txt

@@ -178,7 +178,9 @@ pygithub==1.59.0 \
 pyjwt[crypto]==2.4.0 \
     --hash=sha256:72d1d253f32dbd4f5c88eaf1fdc62f3a19f676ccbadb9dbc5d07e951b2b26daf \
     --hash=sha256:d42908208c699b3b973cbeb01a969ba6a96c821eefb1c5bfe4c390c01d67abba
-    # via pygithub
+    # via
+    #   pygithub
+    #   pyjwt
 pynacl==1.4.0 \
     --hash=sha256:06cbb4d9b2c4bd3c8dc0d267416aaed79906e7b33f114ddbf0911969794b1cc4 \
     --hash=sha256:11335f09060af52c97137d4ac54285bcb7df0cef29014a1a4efe64ac065434c4 \
@@ -207,9 +209,9 @@ six==1.16.0 \
     --hash=sha256:1e61c37477a1626458e36f7b1d82aa5c9b094fa4802892072e49de9c60c4c926 \
     --hash=sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254
     # via pynacl
-slack-sdk==3.21.3 \
-    --hash=sha256:20829bdc1a423ec93dac903470975ebf3bc76fd3fd91a4dadc0eeffc940ecb0c \
-    --hash=sha256:de3c07b92479940b61cd68c566f49fbc9974c8f38f661d26244078f3903bb9cc
+slack-sdk==3.26.0 \
+    --hash=sha256:147946f388ce73b17c377b823759fcb39c0eca7444ca0a942dc12a3940a4f44f \
+    --hash=sha256:b84c2d93163166eb682e290c19334683c2d0f0cb4a5479c809706b44038fdda1
     # via -r requirements.in
 urllib3==1.26.6 \
     --hash=sha256:39fb8672126159acb139a7718dd10806104dec1e2f0f6c88aab05d17df10c8d4 \