Run min test in PR CI workflow

Signed-off-by: Mathias L. Baumann <[email protected]>

Author: Marenz

.github/workflows/ci-pr.yaml

@@ -6,7 +6,7 @@ on:
 env:
   # Please make sure this version is included in the `matrix`, as the
   # `matrix` section can't use `env`, so it must be entered manually
-  DEFAULT_PYTHON_VERSION: '3.11'
+  DEFAULT_PYTHON_VERSION: '3.13'
   # It would be nice to be able to also define a DEFAULT_UBUNTU_VERSION
   # but sadly `env` can't be used either in `runs-on`.
 
@@ -19,8 +19,8 @@ jobs:
       - name: Run nox
         uses: frequenz-floss/[email protected]
         with:
-          python-version: "3.11"
-          nox-session: ci_checks_max
+          python-version: "3.13"
+          nox-session: pytest_min
 
   test-docs:
     name: Test documentation website generation

.github/workflows/ci.yaml

@@ -1,6 +1,7 @@
 name: CI
 
 on:
+  pull_request:
   merge_group:
   push:
     # We need to explicitly include tags because otherwise when adding