chore: add node:16 to the test matrix (#85)

Author: rauno56

.github/workflows/test.yaml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        container: ["node:8", "node:10", "node:12", "node:14"]
+        container: ["node:8", "node:10", "node:12", "node:14", "node:16"]
     runs-on: ubuntu-latest
     container:
       image: ${{ matrix.container }}
@@ -29,7 +29,7 @@ jobs:
 
       - name: Report Coverage
         run: npm run codecov
-        if: ${{ matrix.container }} == 'node:12'
+        if: ${{ matrix.container }} == 'node:14'
 
   browser-tests:
     runs-on: ubuntu-latest