Include node 13 in test matrix

.github/workflows/nodejs.yml

@@ -6,10 +6,10 @@ jobs:
   test:
     name: Test on node ${{ matrix.node_version }} and ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
-    
+
     strategy:
       matrix:
-        node_version: [9, 10, 11, 12]
+        node_version: [9, 10, 11, 12, 13]
         os: [ubuntu-latest, windows-latest, macOS-latest]
 
     steps:
@@ -18,7 +18,7 @@ jobs:
       uses: actions/setup-node@v1
       with:
         node_version: ${{ matrix.node_version }}
-        
+
     - name: npm install & test
       run: |
         npm install