ci: add windows and macos to ci matrix

.github/workflows/build.yml

@@ -44,11 +44,11 @@ permissions:
 jobs:
   test:
     name: Tests
-    runs-on: ubuntu-latest
     strategy:
       matrix:
         node-version: [16.x, 18.x, 20.x]
-
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@8e5e7e5ab8b370d6c329ec480221332ada57f0ab # v3
       - name: Use Node.js ${{ matrix.node-version }}
@@ -56,7 +56,15 @@ jobs:
         with:
           node-version: ${{ matrix.node-version }}
           cache: 'npm'
-      - name: Install latest npm
+      - name: Install latest npm (win)
+        if: ${{ matrix.os == 'windows-latest' }}
+        # for some reason there's a bug in upgrading npm on win, have to install a specific version first
+        # https://github.com/actions/setup-node/issues/623
+        run: |
+          npm install -g npm@8.3.1
+          npm install -g npm@latest
+      - name: Install latest npm (non-win)
+        if: ${{ matrix.os != 'windows-latest' }}
         run: npm install -g npm
       - name: Install dependencies
         uses: bahmutov/npm-install@1a235c31658a322a3b024444759650ee6345c26d # tag=v1