Bump google-cloud-pubsub from 2.19.7 to 2.21.1

Bumps [google-cloud-pubsub](https://github.com/googleapis/python-pubsub) from 2.19.7 to 2.21.1.
- [Release notes](https://github.com/googleapis/python-pubsub/releases)
- [Changelog](https://github.com/googleapis/python-pubsub/blob/main/CHANGELOG.md)
- [Commits](googleapis/python-pubsub@v2.19.7...v2.21.1)

---
updated-dependencies:
- dependency-name: google-cloud-pubsub
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -125,9 +125,9 @@ google-cloud-core==2.3.2 \
     # via
     #   google-cloud-bigquery
     #   google-cloud-storage
-google-cloud-pubsub==2.19.7 \
-    --hash=sha256:443cb58e2440729876f3b0d6046c30c7a873aeb247e5e17f161fe967c91b53fb \
-    --hash=sha256:da5f1eb217c0727befa7c85b9b95e6a89b32b422d548c9cf9a1e029410270b87
+google-cloud-pubsub==2.21.1 \
+    --hash=sha256:31fcf07444b7f813a616c4b650e1fbf1dc998a088fe0059a76164855ac17f05c \
+    --hash=sha256:55a3602ec45bc09626604d712032288a8ee3566145cb83523cff908938f69a4b
     # via -r requirements.in
 google-cloud-storage==2.15.0 \
     --hash=sha256:5d9237f88b648e1d724a0f20b5cde65996a37fe51d75d17660b1404097327dd2 \