Enable ast extension in continuous integration.

Author: drupol

.github/workflows/continuous-integration.yml

@@ -27,7 +27,7 @@ jobs:
               with:
                   php-version: ${{ matrix.php-versions }}
                   extensions: ast,mbstring,xdebug
-
+                  tools: pecl
             - name: Get Composer Cache Directory
               id: composer-cache
               run: echo "::set-output name=dir::$(composer config cache-files-dir)"