chore: support Node 15 (#118)

Author: ehmicky

.github/workflows/workflow.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
-        node-version: [8.3.0, 14]
+        node-version: [8.3.0, 15]
         exclude:
           - os: macOS-latest
             node-version: 8.3.0
@@ -33,10 +33,10 @@ jobs:
         run: npm ci
       - name: Build For Browser
         run: npm run build
-        if: "${{ matrix.node-version == '14' }}"
+        if: "${{ matrix.node-version == '15' }}"
       - name: Linting
         run: npm run format:ci
-        if: "${{ matrix.node-version == '14' }}"
+        if: "${{ matrix.node-version == '15' }}"
       - name: Tests
         run: npm run test:ci
       - name: Get test coverage flags