Use native git checkout and streamline tests in Gitea workflows

.gitea/workflows/tests.yaml

@@ -13,18 +13,15 @@ jobs:
       image: composer:2
 
     steps:
-      - uses: actions/checkout@v3
+      - name: Checkout
+        run: |
+          git init .
+          git remote add origin "https://${{ github.actor }}:${{ secrets.GITHUB_TOKEN }}@$(echo "${{ github.server_url }}" | sed -E 's|https?://||')/${{ github.repository }}.git"
+          git fetch --depth 1 origin "${{ github.ref }}"
+          git checkout FETCH_HEAD
 
       - name: Install Composer dependencies
         run: composer install --no-interaction --prefer-dist
 
       - name: Run PHPUnit
         run: vendor/bin/phpunit
-        if: always()
-
-      - name: Run Psalm
-        run: |
-          curl -sSL https://github.com/vimeo/psalm/releases/download/4.30.0/psalm.phar -o /usr/local/bin/psalm
-          chmod +x /usr/local/bin/psalm
-          psalm --no-cache
-        if: always()