Add postgis to CI setup

.github/workflows/ci.yml

@@ -49,6 +49,7 @@ jobs:
         run: |
           sudo apt-get install -qq postgis
           dpkg --listfiles postgis
+          ls -lR /usr/share/postgresql
 
       # We don't have to specify the ruby version, or grab it from .ruby-verion. This action supports reading the
       # version from .ruby-version itself