Don't run antora task on Windows CI builds

.github/workflows/ci.yml

@@ -72,7 +72,7 @@ jobs:
           GRADLE_ENTERPRISE_ACCESS_KEY: ${{ secrets.GRADLE_ENTERPRISE_SECRET_ACCESS_KEY }}
           GRADLE_ENTERPRISE_CACHE_USERNAME: ${{ secrets.GRADLE_ENTERPRISE_CACHE_USER }}
           GRADLE_ENTERPRISE_CACHE_PASSWORD: ${{ secrets.GRADLE_ENTERPRISE_CACHE_PASSWORD }}
-        run: ./gradlew build
+        run: ./gradlew build ${{ runner.os == 'Windows' && '--exclude-task antora' || ''}}
       - name: Send notification
         uses: ./.github/actions/send-notification
         if: always()