ci: bound the GitHub test jobs so a stall fails before the 6h limit

The previous commit makes a stalled test run dump diagnostics, but the job
itself still idles until GitHub's six-hour hard limit before it is
cancelled. Give the test jobs an explicit timeout-minutes so that a hang
fails the job within a few hours instead, shortly after the ci/ stall
watchdog has printed its diagnostics, and GitHub tears down the job's
process tree cleanly. Three hours leaves ample margin over a healthy run
(well under two hours) while still saving half of the wasted budget.

Signed-off-by: Michael Montalbo <mmontalbo@gmail.com>

Author: mmontalbo

.github/workflows/main.yml

@@ -340,6 +340,9 @@ jobs:
       CI_JOB_IMAGE: ${{matrix.vector.pool}}
       TEST_OUTPUT_DIRECTORY: ${{github.workspace}}/t
     runs-on: ${{matrix.vector.pool}}
+    # A stalled run otherwise idles until GitHub's 6h hard limit; fail
+    # sooner, shortly after the ci/ stall watchdog has dumped diagnostics.
+    timeout-minutes: 180
     steps:
     - uses: actions/checkout@v6
     - run: ci/install-dependencies.sh
@@ -420,6 +423,9 @@ jobs:
       CI_JOB_IMAGE: ${{matrix.vector.image}}
       CUSTOM_PATH: /custom
     runs-on: ubuntu-latest
+    # A stalled run otherwise idles until GitHub's 6h hard limit; fail
+    # sooner, shortly after the ci/ stall watchdog has dumped diagnostics.
+    timeout-minutes: 180
     container: ${{matrix.vector.image}}
     steps:
     - name: prepare libc6 for actions