Postgres: Add postgres versions 11 and 12 to version selector (#24750)

Closes #24320

public/app/plugins/datasource/postgres/config_ctrl.ts

@@ -69,5 +69,7 @@ export class PostgresConfigCtrl {
     { name: '9.5', value: 905 },
     { name: '9.6', value: 906 },
     { name: '10', value: 1000 },
+    { name: '11', value: 1100 },
+    { name: '12', value: 1200 },
   ];
 }