👷 Upgrade postgres:latest Docker digest to b6b4d0b

Author: renovate[bot]

Auto-Devops/Ruby.gitlab-ci.yml

@@ -58,7 +58,7 @@ variables:
     - .install_cache
   stage: test
   services:
-    - postgres:latest@sha256:6b841c8f6a819884207402f1209a8116844365df15fca8cf556fc54a24c70800
+    - postgres:latest@sha256:b6b4d0b75c699a2c94dfc5a94fe09f38630f3b67ab0e1653ede1b7ac8e13c197
     - redis:latest@sha256:1d38c52e8d34c0471350c545d7a9066c95f5a6b9f24c74209331c03c496e2290
   variables:
     RAILS_ENV: test