Use pnpm (#24)

Author: TooTallNate

.github/workflows/test.yml

@@ -9,18 +9,18 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x]
+        node-version: [14.x, 16.x, 18.x]
 
     steps:
     - uses: actions/checkout@v1
+    - uses: pnpm/action-setup@v2
+      with:
+        version: 7.18.2
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v3
       with:
         node-version: ${{ matrix.node-version }}
-    - name: npm install, build, and test
-      run: |
-        npm install
-        npm run build --if-present
-        npm test
-      env:
-        CI: true
+        cache: 'pnpm'
+    - run: pnpm install --frozen-lockfile
+    - run: pnpm build
+    - run: pnpm test