Docker alpine: Fix for PEP-668 (#3463)

* fix pip use (PEP 668) after alpine docker image was updated to alpine 3.19,
* set PYTHONPATH
* add pip --no-cache-dir option

docker/alpine/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.19 as common
+FROM python:3-alpine3.19 as common
 
 # Based on:
 # https://github.com/mundialis/docker-grass-gis/blob/master/Dockerfile
@@ -79,7 +79,7 @@ RUN echo "Install Python";\
     apk add --no-cache $PYTHONBIN && \
     $PYTHONBIN -m ensurepip && \
     rm -r /usr/lib/python*/ensurepip && \
-    pip$PYTHON_VERSION install --upgrade pip setuptools && \
+    pip$PYTHON_VERSION install --no-cache-dir --upgrade pip setuptools && \
     if [ ! -e /usr/bin/pip ]; then ln -s pip$PYTHON_VERSION /usr/bin/pip ; fi && \
     if [ ! -e /usr/bin/python ]; then ln -sf /usr/bin/$PYTHONBIN /usr/bin/python; fi && \
     rm -r /root/.cache; \
@@ -206,7 +206,8 @@ ENV GRASSBIN="/usr/local/bin/grass" \
     # https://proj.org/usage/environmentvars.html#envvar-PROJ_NETWORK
     PROJ_NETWORK=ON \
     GRASSBIN=grass \
-    LC_ALL="en_US.UTF-8"
+    LC_ALL="en_US.UTF-8" \
+    PYTHONPATH="/usr/local/grass/etc/python:$PYTHONPATH"
 
 # Copy GRASS GIS and GDAL GRASS driver from build image
 COPY --from=build /usr/local/bin/grass /usr/local/bin/grass
@@ -218,7 +219,7 @@ COPY docker/testdata/test_grass_session.py docker/alpine/grass_tests.sh /scripts
 COPY docker/testdata/test_grass_session.py /scripts/
 
 # install external Python API
-RUN pip3 install --upgrade pip six grass-session --ignore-installed six; \
+RUN pip3 install --no-cache-dir --upgrade pip six grass-session --ignore-installed six; \
     ln -sf /usr/local/grass $(grass --config path); \
     # run some tests and cleanup
     $SHELL /scripts/grass_tests.sh \