Update Dockerfile

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

sparkjava/sparkjava/Dockerfile

@@ -10,16 +10,13 @@ COPY src /workdir/server/src
 RUN mvn --batch-mode clean compile assembly:single
 
 FROM build AS dev-envs
-RUN <<EOF
-apt-get update
-apt-get install -y --no-install-recommends git
-EOF
+RUN apt update && \
+apt install -y --no-install-recommends git
 
-RUN <<EOF
-useradd -s /bin/bash -m vscode
-groupadd docker
+
+RUN useradd -s /bin/bash -m vscode && \
+groupadd docker && \
 usermod -aG docker vscode
-EOF
 # install Docker tools (cli, buildx, compose)
 COPY --from=gloursdocker/docker / /
 CMD ["java", "-jar", "target/app.jar" ]