Fixes for installer (#7344)

* - move reqs file to contrib
- detect previously used python version
- safe extra requirements to INSTALLER_EXTRA

* add missing fi

* move site setting

.github/workflows/docker.yaml

@@ -73,7 +73,7 @@ jobs:
           python-version: ${{ env.python_version }}
       - name: Version Check
         run: |
-          pip install --require-hashes -r .github/requirements.txt
+          pip install --require-hashes -r contrib/dev_reqs/requirements.txt
           python3 .github/scripts/version_check.py
           echo "git_commit_hash=$(git rev-parse --short HEAD)" >> $GITHUB_ENV
           echo "git_commit_date=$(git show -s --format=%ci)" >> $GITHUB_ENV