ci: put a 10 minute timeout on the Debian build (#8795)

This usually takes around 2 minutes. I just saw a runaway one spending
30+ minutes.

.github/workflows/test.yml

@@ -857,6 +857,7 @@ jobs:
   test-debian-13:
     name: Test build on Debian 13
     runs-on: namespace-profile-ghostty-sm
+    timeout-minutes: 10
     needs: [test, build-dist]
     steps:
       - name: Install and configure Namespace CLI