chore(deps): bump filelock from 3.13.1 to 3.20.3 in /.kokoro

Bumps [filelock](https://github.com/tox-dev/py-filelock) from 3.13.1 to 3.20.3.
- [Release notes](https://github.com/tox-dev/py-filelock/releases)
- [Changelog](https://github.com/tox-dev/filelock/blob/main/docs/changelog.rst)
- [Commits](tox-dev/filelock@3.13.1...3.20.3)

---
updated-dependencies:
- dependency-name: filelock
  dependency-version: 3.20.3
  dependency-type: indirect
...

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

Author: dependabot[bot]

.kokoro/requirements.txt

@@ -171,9 +171,9 @@ docutils==0.20.1 \
     --hash=sha256:96f387a2c5562db4476f09f13bbab2192e764cac08ebbf3a34a95d9b1e4a59d6 \
     --hash=sha256:f08a4e276c3a1583a86dce3e34aba3fe04d02bba2dd51ed16106244e8a923e3b
     # via readme-renderer
-filelock==3.13.1 \
-    --hash=sha256:521f5f56c50f8426f5e03ad3b281b490a87ef15bc6c526f168290f0c7148d44e \
-    --hash=sha256:57dbda9b35157b05fb3e58ee91448612eb674172fab98ee235ccb0b5bee19a1c
+filelock==3.20.3 \
+    --hash=sha256:18c57ee915c7ec61cff0ecf7f0f869936c7c30191bb0cf406f1341778d0834e1 \
+    --hash=sha256:4b0dda527ee31078689fc205ec4f1c1bf7d56cf88b6dc9426c4f230e46c2dce1
     # via virtualenv
 gcp-docuploader==0.6.5 \
     --hash=sha256:30221d4ac3e5a2b9c69aa52fdbef68cc3f27d0e6d0d90e220fc024584b8d2318 \