Speed up tests (#638)

.github/actions/setup_xapian/action.yml

@@ -0,0 +1,10 @@
+name: "Setup xapian"
+description: "Setup the xapian indexes"
+runs:
+  using: composite
+  steps:
+    - name: Setup xapian index
+      run: |
+        mkdir -p /dev/shm/search_indexes
+        ln -s /dev/shm/search_indexes sith/search_indexes
+      shell: bash