Cleanup backend dockerfile

- Upgrade pdm and pydebug versions
- Reduce RUN layers for apt steps
- Remove gunicorn workers parameter to allow for WEB_CONCURRENCY env

Signed-off-by: eternaltyro <230743+eternaltyro@users.noreply.github.com>

scripts/docker/Dockerfile.backend

@@ -25,7 +25,7 @@ FROM base as extract-deps
 RUN pip install --no-cache-dir --upgrade pip
 WORKDIR /opt/python
 COPY pyproject.toml pdm.lock README.md /opt/python/
-RUN pip install --no-cache-dir pdm==2.7.4
+RUN pip install --no-cache-dir pdm==2.8.0
 RUN pdm export --prod --without-hashes > requirements.txt
 
 
@@ -34,9 +34,8 @@ FROM base as build
 RUN pip install --no-cache-dir --upgrade pip
 WORKDIR /opt/python
 # Setup backend build-time dependencies
-RUN apt-get update
-RUN apt-get install --no-install-recommends -y build-essential
-RUN apt-get install --no-install-recommends -y \
+RUN apt-get update && apt-get install --no-install-recommends -y \
+        build-essential \
         postgresql-server-dev-15 \
         python3-dev \
         libffi-dev \
@@ -79,7 +78,7 @@ COPY manage.py .
 
 FROM runtime as debug
 RUN pip install --user --no-warn-script-location \
-    --no-cache-dir debugpy==1.6.7
+    --no-cache-dir debugpy==1.8.1
 CMD ["python", "-m", "debugpy", "--wait-for-client", "--listen", "0.0.0.0:5678", \
     "-m", "gunicorn", "-c", "python:backend.gunicorn", "manage:application", \
     "--reload", "--log-level", "error"]
@@ -93,4 +92,4 @@ RUN python -c "import compileall; compileall.compile_path(maxlevels=10, quiet=1)
 RUN python -m compileall .
 USER appuser:appuser
 CMD ["gunicorn", "-c", "python:backend.gunicorn", "manage:application", \
-    "--workers", "1", "--log-level", "error"]
+     "--log-level", "error"]