build(deps): bump certifi from 2022.12.7 to 2023.7.22 in /.kokoro

Bumps [certifi](https://github.com/certifi/python-certifi) from 2022.12.7 to 2023.7.22.
- [Commits](certifi/python-certifi@2022.12.07...2023.07.22)

---
updated-dependencies:
- dependency-name: certifi
  dependency-type: direct:production
...

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

.kokoro/requirements.txt

@@ -12,9 +12,9 @@ cachetools==4.2.4 \
     --hash=sha256:89ea6f1b638d5a73a4f9226be57ac5e4f399d22770b92355f92dcb0f7f001693 \
     --hash=sha256:92971d3cb7d2a97efff7c7bb1657f21a8f5fb309a37530537c71b1774189f2d1
     # via google-auth
-certifi==2022.12.7 \
-    --hash=sha256:35824b4c3a97115964b408844d64aa14db1cc518f6562e8d7261699d1350a9e3 \
-    --hash=sha256:4ad3232f5e926d6718ec31cfc1fcadfde020920e278684144551c91769c7bc18
+certifi==2023.7.22 \
+    --hash=sha256:539cc1d13202e33ca466e88b2807e29f4c13049d6d87031a3c110744495cb082 \
+    --hash=sha256:92d6037539857d8206b8f6ae472e8b77db8058fec5937a1ef3f54304089edbb9
     # via
     #   -r requirements.in
     #   requests