Use env check action in old unit tests [skip azp][skip circle]

Author: tsbinns

.github/workflows/tests.yml

@@ -149,7 +149,11 @@ jobs:
       - run: bash ./tools/github_actions_verify_python.sh "${{ matrix.python }}"
       - run: bash ./tools/github_actions_dependencies.sh
         timeout-minutes: 10
-      - run: python ./tools/github_actions_check_old_env.py
+      - name: Run MNE-Tools action
+        uses: tsbinns/mne-tools/actions/check-environment@add_tools
+        with:
+          project-root: ${{ github.workspace }}
+          groups: lockfile_extras
         if: matrix.kind == 'old'
       # Minimal commands on Linux (macOS stalls)
       - uses: actions/cache@v5.0.5

tools/github_actions_dependencies.sh

@@ -29,7 +29,7 @@ elif [[ "${MNE_CI_KIND}" == "old" ]]; then
 	STD_ARGS="--progress-bar off"
 	echo "::group::Syncing old environment dependencies from lockfile using uv"
 	uv pip sync ${SCRIPT_DIR}/pylock.ci-old.toml
-	uv pip install pip tomlkit ${MNE_QT_BACKEND}
+	uv pip install pip ${MNE_QT_BACKEND}
 	echo "::endgroup::"
 elif [[ "${MNE_CI_KIND}" == "pip-ft" ]]; then
 	# This one is free-threaded so can't have PySide6/PyQt6 as of 2026/06/16