Workflows: Install SVN before running tests. (#254)

Subversion was removed from GitHub Actions' default packages for Ubuntu 24.

The tests installer uses Subversion internally. This change installs Subversion.

Author: costdev

.github/workflows/phpunit-tests.yml

@@ -35,6 +35,9 @@ jobs:
           php-version: ${{ matrix.php-version }}
           tools: phpunit-polyfills:1.1
 
+      - name: Install SVN
+        run: sudo apt install -y subversion
+
       - name: Setup tests
         run: bash bin/install-wp-tests.sh wordpress_tests root root 127.0.0.1 latest true