ci: add reasonable timeouts for jobs

The timeouts are at least 3x the expected time to complete the jobs.

This is particularly relevant for the `pytest` job. Occasionally, it hangs while running tests that do network things, and the job only times out after 6 hours.

.github/workflows/check-frontend.yml

@@ -15,6 +15,7 @@ defaults:
 jobs:
   check-frontend:
     runs-on: ubuntu-latest
+    timeout-minutes: 10 # expected run time: <2 min
     steps:
       - uses: actions/checkout@v4
 

.github/workflows/check-pytest.yml

@@ -44,6 +44,7 @@ jobs:
             github-env: $env:GITHUB_ENV
     name: ${{ matrix.pytorch }} on ${{ matrix.python-version }}
     runs-on: ${{ matrix.os }}
+    timeout-minutes: 30 # expected run time: <10 min, depending on platform
     env:
       PIP_USE_PEP517: '1'
     steps:

.github/workflows/check-python.yml

@@ -13,6 +13,7 @@ on:
 jobs:
   check-backend:
     runs-on: ubuntu-latest
+    timeout-minutes: 5 # expected run time: <1 min
     steps:
       - uses: actions/checkout@v4