chore: Switch to NPM (#40)

Author: rschristian

.github/workflows/ci.yml

@@ -16,11 +16,11 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 18
-          cache: yarn
+          node-version: 22
+          cache: npm
 
       - name: Install dependencies
-        run: yarn install --frozen-lockfile
+        run: npm ci
 
       - name: Tests
-        run: yarn test
+        run: npm run test