Adapt CI to new xapian install process

.github/actions/setup_project/action.yml

@@ -6,13 +6,13 @@ runs:
     - name: Install apt packages
       uses: awalsh128/cache-apt-pkgs-action@latest
       with:
-        packages: gettext libxapian-dev libgraphviz-dev
+        packages: gettext libgraphviz-dev
         version: 1.0  # increment to reset cache
 
     - name: Install dependencies
       run: |
         sudo apt update
-        sudo apt install gettext libxapian-dev libgraphviz-dev
+        sudo apt install gettext libgraphviz-dev
       shell: bash
 
     - name: Set up python
@@ -48,6 +48,10 @@ runs:
       run: poetry install -E testing -E docs
       shell: bash
 
+    - name: Install xapian
+      run: poetry run ./manage.py install_xapian
+      shell: bash
+
     - name: Compile gettext messages
       run: poetry run ./manage.py compilemessages
       shell: bash