Update flask dockerfile

Author: pythoninthegrass

devops/tilt/Dockerfile

@@ -1,14 +1,18 @@
 # syntax=docker/dockerfile:1.5
-FROM python:3.10.10-slim-buster
+
+ARG PYTHON_VER=${PYTHON_VER:-3.10.10}
+
+FROM python:${PYTHON_VER}-slim-buster
 
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1
 
 WORKDIR /app
 
 COPY requirements.txt .
-RUN pip install --upgrade pip \
-    && pip install -r requirements.txt
+
+RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt
+
 COPY . .
 
 ENTRYPOINT ["python", "/app/app.py"]