chore: simplified Dockerfile

Dockerfile

@@ -6,15 +6,10 @@ RUN apt-get update \
  && apt-get install -y --no-install-recommends \
       git \
       unzip \
- && php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');" \
- && php -r "copy('https://composer.github.io/installer.sig', 'composer-setup.php.sig');" \
- && php -r "if (trim(hash_file('SHA384', 'composer-setup.php')) === trim(file_get_contents('composer-setup.php.sig'))) { echo 'Installer verified' . PHP_EOL; exit(0); } else { echo 'Installer corrupt' . PHP_EOL; unlink('composer-setup.php'); unlink('composer-setup.php.sig'); exit(-1); }" \
- && php composer-setup.php \
- && php -r "unlink('composer-setup.php'); unlink('composer-setup.php.sig');" \
- && mv composer.phar /usr/local/bin/composer \
  && apt-get clean \
  && rm -rf /var/lib/apt/lists/* \
 ;
+COPY --from=composer:2 /usr/bin/composer /usr/local/bin/composer
 # endregion
 
 # region included composer-library