add venv installation in backend Dockerfile, to run build on azure agent

Author: Olesia Solonko

pygeoapi/docker/Dockerfile.pygeoapi

@@ -21,6 +21,7 @@ RUN apt-get update \
     zlib1g-dev \
     libprotobuf-dev \
     protobuf-compiler \
+    python3-venv \
     && git clone https://github.com/mapbox/tippecanoe.git /tmp/tippecanoe \
     && cd /tmp/tippecanoe \
     && make -j \
@@ -30,6 +31,10 @@ RUN apt-get update \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
+RUN python3 -m venv /opt/venv \
+    && /opt/venv/bin/python -m pip install --upgrade pip setuptools wheel
+ENV PATH="/opt/venv/bin:$PATH"
+
 # Install Application Insights for Python
 RUN pip install opencensus-ext-azure opencensus-ext-flask opencensus-ext-requests