chore(deps): update postgresql to v18

Author: renovate[bot]

umbrella-charts/coder/Chart.yaml

@@ -7,7 +7,7 @@ version: 1.0.0
 
 dependencies:
 - name: postgresql
-  version: 16.7.27
+  version: 18.1.15
   repository: oci://registry-1.docker.io/bitnamicharts
 - name: coder
   version: 2.29.1

umbrella-charts/grafana/Chart.yaml

@@ -7,7 +7,7 @@ version: 1.0.0
 
 dependencies:
 - name: postgresql
-  version: 16.7.27
+  version: 18.1.15
   repository: oci://registry-1.docker.io/bitnamicharts
 - name: grafana
   version: 10.1.0