add pylint to list of required linting tools

With pylint being run in the CI, passing it is required now.

.github/workflows/ci-tests.yml

@@ -47,12 +47,16 @@ jobs:
 
             - name: Install test prerequsites
               run: |
-                   sudo apt-get install -y -qq php-codesniffer
+                   sudo apt-get install -y -qq php-codesniffer pylint
                    sudo pip3 install behave
 
             - name: PHP linting
               run: phpcs --report-width=120 .
 
+            - name: Python linting
+              run: |
+                   pylint nominatim
+
             - name: PHP unit tests
               run: phpunit ./
               working-directory: test/php