chore: support Node 15

Author: ehmicky

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
-        node-version: [10.13.0, 14.x]
+        node-version: [10.13.0, 15.x]
         exclude:
           - os: macOS-latest
             node-version: 10.13.0