chore(container): simplify creation of dynamically allocated system user

Author: nanotaboada

Dockerfile

@@ -62,8 +62,7 @@ COPY --chmod=755        scripts/healthcheck.sh      ./healthcheck.sh
 COPY --chmod=755        storage                     ./docker-compose
 
 # Add non-root user and make volume mount point writable
-RUN groupadd --system fastapi && \
-    adduser --system --ingroup fastapi --disabled-password --gecos '' fastapi && \
+RUN adduser --system --disabled-password --group fastapi && \
     mkdir -p /storage && \
     chown fastapi:fastapi /storage