fix: increase nightly slow-integration-tests timeout to 45 minutes (#1387)

The full test suite with -race now takes ~30 minutes, causing the
30-minute job timeout to cancel runs before completion.

Co-authored-by: Ben Coombs <bjcoombs@users.noreply.github.com>

Author: bjcoombs

.github/workflows/nightly.yml

@@ -89,7 +89,7 @@ jobs:
   slow-integration-tests:
     name: Slow Integration Tests
     runs-on: ubuntu-latest
-    timeout-minutes: 30
+    timeout-minutes: 45
     # Note: No postgres service container needed - tests use testcontainers
     # which manage their own ephemeral containers with proper isolation.