Update Dockerfile

Signed-off-by: techopsmasters <163403479+techopsmasters@users.noreply.github.com>

nginx-flask-mysql/backend/Dockerfile

@@ -19,15 +19,11 @@ CMD ["flask", "run"]
 
 FROM builder AS dev-envs
 
-RUN <<EOF
-apk update
-apk add git
-EOF
+RUN apt update && \
+apt add git
 
-RUN <<EOF
-addgroup -S docker
+RUN addgroup -S docker && \
 adduser -S --shell /bin/bash --ingroup docker vscode
-EOF
 
 # install Docker tools (cli, buildx, compose)
 COPY --from=gloursdocker/docker / /