buildworker,buildmaster: Use venv for Pip

Debian 12 complains if using Pip without a virtualenv since it could
break the system.

Signed-off-by: Paul Spooren <mail@aparcar.org>

docker/buildmaster/Dockerfile

@@ -46,12 +46,15 @@ RUN \
  locales \
  pv \
  pwgen \
+ python3-venv \
  python3-pip \
  signify-openbsd \
  wget && \
  apt-get clean && \
  localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8
 
+RUN python3 -m venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
 RUN pip3 install -U pip
 RUN \
  pip3 install \
@@ -63,15 +66,16 @@ RUN \
  "buildbot-worker==$BUILDBOT_VERSION" \
  pyOpenSSL \
  service_identity
+
 RUN \
  sed -i \
  's/Welcome to buildbot/Welcome to OpenWrt buildbot/' \
- /usr/local/lib/python*/dist-packages/buildbot_www/static/scripts.js
+ /opt/venv/lib/python*/site-packages/buildbot_www/static/scripts.js
 
 RUN \
  sed -i \
  "s;\"col-sm-12\"><ul><li ng-repeat;\"col-sm-12\"><ul><li>OpenWrt version: <a href=\"https://git.openwrt.org/$OPENWRT_VERSION\">$OPENWRT_VERSION</a></li><li ng-repeat;" \
- /usr/local/lib/python*/dist-packages/buildbot_www/static/scripts.js
+ /opt/venv/lib/python*/site-packages/buildbot_www/static/scripts.js
 
 ENV LANG=en_US.utf8