🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Author: gcf-owl-bot[bot]

.github/workflows/unittest.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+        python: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
     steps:
     - name: Checkout
       uses: actions/checkout@v4

.kokoro/presubmit/system-3.8.cfg

@@ -0,0 +1,7 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Only run this nox session.
+env_vars: {
+    key: "NOX_SESSION"
+    value: "system-3.8"
+}