Run the app manager using the dockerized python

When using #!/usr/bin/python3, we end up using Debian's system-wide
python rather than the copy shipped in the docker container. This
pollutes the generated virtualenv with the wheels generated by Debian
packaging, rather than the expected upstream wheels.

scripts/Dockerfile

@@ -14,17 +14,17 @@ RUN apt-get -y update && \
       libsvn-dev libapr1-dev libaprutil1-dev \
       libpython3-dev \
       libpq-dev \
-      python3-click \
-      python3-venv \
-      python3-yaml \
-      python3-dulwich \
     && \
     apt clean
 
 RUN mkdir -p /opt/scripts/
 COPY app_manager.py /opt/scripts/
+COPY requirements.txt /opt/scripts/
 RUN chmod +x /opt/scripts/app_manager.py
 
+RUN pip install -U pip setuptools wheel && \
+    pip install -r /opt/scripts/requirements.txt
+
 # This expects the /src/ to be mounted on swh-apps repository folder at runtime
 ENV SWH_APPS_DIR=/src/apps
 

scripts/app_manager.py

-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 # Copyright (C) 2022-2023  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution

scripts/requirements.txt

+click
+dulwich
+PyYAML