build(deps): bump requests

Bumps [requests](https://github.com/psf/requests) from 2.28.1 to 2.31.0.
- [Release notes](https://github.com/psf/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/main/HISTORY.md)
- [Commits](psf/requests@v2.28.1...v2.31.0)

---
updated-dependencies:
- dependency-name: requests
  dependency-type: indirect
...

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

synthtool/gcp/templates/python_library/.kokoro/requirements.txt

@@ -419,9 +419,9 @@ readme-renderer==37.3 \
     --hash=sha256:cd653186dfc73055656f090f227f5cb22a046d7f71a841dfa305f55c9a513273 \
     --hash=sha256:f67a16caedfa71eef48a31b39708637a6f4664c4394801a7b0d6432d13907343
     # via twine
-requests==2.28.1 \
-    --hash=sha256:7c5599b102feddaa661c826c56ab4fee28bfd17f5abca1ebbe3e7f19d7c97983 \
-    --hash=sha256:8fefa2a1a1365bf5520aac41836fbee479da67864514bdb821f31ce07ce65349
+requests==2.31.0 \
+    --hash=sha256:58cd2187c01e70e6e26505bca751777aa9f2ee0b7f4300988b709f44e013003f \
+    --hash=sha256:942c5a758f98d790eaed1a29cb6eefc7ffb0d1cf7af05c3d2791656dbd6ad1e1
     # via
     #   gcp-releasetool
     #   google-api-core