Maintenance: Ensure correct time zone for CI (GitHub).

.github/workflows/ci.yaml

@@ -23,6 +23,7 @@ jobs:
     env:
       RAILS_ENV: test
       Z_LOCALES: "en-us:de-de"
+      TZ: 'Europe/London'
       REDIS_URL: redis://redis:6379
       # Compile assets only once.
       CI_SKIP_ASSETS_PRECOMPILE: 'true'
@@ -48,4 +49,4 @@ jobs:
       - name: Lint
         run: .github/workflows/ci/lint.sh
       - name: Test
-        run: .github/workflows/ci/test.sh
+        run: .github/workflows/ci/test.sh