build(Dockerfile): use dedicated user

Author: Lujeni

Dockerfile

@@ -5,6 +5,10 @@ WORKDIR /usr/src/app
 COPY requirements.txt requirements.txt
 RUN pip3 install -r requirements.txt
 
+RUN groupadd --gid 1000 appuser \
+    && useradd --uid 1000 --gid appuser --shell /bin/bash --create-home appuser
+
+USER appuser
 COPY gitlab2sentry/ gitlab2sentry/
 COPY run.py run.py
 COPY g2s.yaml g2s.yaml