fix: use composer install instead of update in Dockerfile for deterministic builds

Author: ChiragAgg5k

Dockerfile

@@ -4,7 +4,7 @@ WORKDIR /usr/local/src/
 COPY composer.lock /usr/local/src/
 COPY composer.json /usr/local/src/
 
-RUN composer update \
+RUN composer install \
     --ignore-platform-reqs \
     --optimize-autoloader \
     --no-plugins \