Run CommonJS/ESM usage tests on more Node.js versions

As it's very interesting to see how the package works for different
major versions of Node.js, not just 12.x or 13.x as before.

.github/workflows/usage.yml

@@ -51,13 +51,17 @@ jobs:
   common-js-usage:
     runs-on: ubuntu-latest
 
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 14.x, 15.x]
+
     needs: package
     steps:
       - uses: actions/checkout@v1
       - name: Setup Node.js
         uses: actions/setup-node@v1
         with:
-          node-version: 12.x
+          node-version: ${{ matrix.node-version }}
       - name: Get package tarball from package step
         uses: actions/download-artifact@v2
         with:
@@ -74,13 +78,17 @@ jobs:
   esm-usage:
     runs-on: ubuntu-latest
 
+    strategy:
+      matrix:
+        node-version: [14.x, 15.x]
+
     needs: package
     steps:
       - uses: actions/checkout@v1
       - name: Setup Node.js
         uses: actions/setup-node@v1
         with:
-          node-version: '>=13.2.0'
+          node-version: ${{ matrix.node-version }}
       - name: Get package tarball from package step
         uses: actions/download-artifact@v2
         with: