Fail on pod lib lint warnings (#82)

.github/workflows/tests.yml

@@ -27,7 +27,7 @@ jobs:
     - name: Install Ruby gems with Bundler
       run: bundle install
     - name: Lint podspec using local source
-      run: pod lib lint --verbose --allow-warnings ${{ matrix.flags }}
+      run: pod lib lint --verbose ${{ matrix.flags }}
 
   spm-build-test:
     runs-on: macOS-latest