Run app as non-root with venv

Dockerfile

@@ -6,8 +6,16 @@ ENV PYTHONDONTWRITEBYTECODE=1 \
 WORKDIR /app
 
 COPY pyproject.toml README.md ddgs_cli.py app.py ./
-RUN python -m pip install --no-cache-dir --upgrade pip \
-    && python -m pip install --no-cache-dir .
+RUN python -m venv /opt/venv \
+    && /opt/venv/bin/pip install --no-cache-dir --upgrade pip \
+    && /opt/venv/bin/pip install --no-cache-dir .
+
+ENV PATH="/opt/venv/bin:$PATH"
+
+RUN useradd --uid 1000 --create-home appuser \
+    && chown -R 1000:1000 /app
+
+USER 1000
 
 EXPOSE 7860