Add postgres 15 for CI test

Signed-off-by: Khiem Doan <[email protected]>

Author: khiemdoan

.circleci/config.yml

@@ -61,6 +61,7 @@ workflows:
             - circleci/postgres:12
             - circleci/postgres:13
             - cimg/postgres:14.1
+            - cimg/postgres:15.1
     - prometheus/build:
         name: build
         parallelism: 3

README.md

@@ -7,7 +7,7 @@
 
 Prometheus exporter for PostgreSQL server metrics.
 
-CI Tested PostgreSQL versions: `9.4`, `9.5`, `9.6`, `10`, `11`, `12`, `13`, `14`
+CI Tested PostgreSQL versions: `9.4`, `9.5`, `9.6`, `10`, `11`, `12`, `13`, `14`, `15`
 
 ## Quick Start
 This package is available for Docker: