Changes in response to PG 15 update on test server (#1026)

I just updated the test deployment server to use PG 15. These are some
changes in response to that.

.deployment/setup-server.yml

@@ -75,14 +75,6 @@
         cmd: postgresql-setup --initdb
         creates: /var/lib/pgsql/data/postgresql.conf
 
-    - name: set auth to scram-sha-256
-      become: true
-      lineinfile:
-        path: /var/lib/pgsql/data/postgresql.conf
-        regexp: '^password_encryption'
-        line: "password_encryption = 'scram-sha-256'"
-      notify: restart postgresql
-
     - name: configure postgres access
       become: true
       copy:

util/containers/docker-compose.yml

@@ -36,7 +36,7 @@ services:
 
   # A PostgreSQL database for Tobira.
   tobira-dev-database:
-    image: docker.io/library/postgres:15
+    image: docker.io/library/postgres:12
     restart: unless-stopped
     ports:
       - 127.0.0.1:5432:5432