install composer in Docker and remove setup-php step

.github/workflows/ci.yml

@@ -66,12 +66,6 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
 
-      - name: Setup PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: 8.1
-          coverage: pcov
-
       - name: Get composer cache directory
         id: composer-cache
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"

Dockerfile

@@ -32,6 +32,9 @@ RUN pecl install redis-5.3.7 sqlsrv pdo_sqlsrv \
     && printf "; priority=30\nextension=pdo_sqlsrv.so\n" > /etc/php/$PHP_VERSION/mods-available/pdo_sqlsrv.ini \
     && phpenmod -v $PHP_VERSION redis sqlsrv pdo_sqlsrv
 
+# install composer
+COPY --from=composer:latest /usr/bin/composer /usr/local/bin/composer
+
 # set the system timezone
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime \
     && echo $TZ > /etc/timezone