ci: remove Node 12 from the test matrix

Reference: https://github.com/nodejs/Release

Author: darrachequesne

.github/workflows/ci.yml

@@ -16,7 +16,10 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x, 18.x]
+        node-version:
+          - 14
+          - 16
+          - 18
 
     services:
       postgres: