chore: add node 12 test

Author: ascorbic

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
-        node-version: ['*']
+        node-version: [12, '*']
         exclude:
           - os: macOS-latest
             node-version: 12