Migrate from Yarn@1 to NPM

.github/workflows/ci-build.yml

@@ -20,9 +20,9 @@ jobs:
       - uses: volta-cli/action@v1
         with:
           node-version: 10.x
-      - run: yarn install --frozen-lockfile
-      - run: yarn lint
-      - run: yarn test
+      - run: npm ci
+      - run: npm run lint
+      - run: npm run test
 
   floating-dependencies:
     timeout-minutes: 10
@@ -34,8 +34,8 @@ jobs:
       - uses: volta-cli/action@v1
         with:
           node-version: 12.x
-      - run: yarn install --no-lockfile
-      - run: yarn test
+      - run: npm ci
+      - run: npm test
 
   try-scenarios:
     timeout-minutes: 10
@@ -68,6 +68,6 @@ jobs:
         with:
           node-version: 12.x
       - name: install dependencies
-        run: yarn install --frozen-lockfile
+        run: npm ci
       - name: test
         run: node_modules/.bin/ember try:one ${{ matrix.ember-try-scenario }} --skip-cleanup

CONTRIBUTING.md

@@ -4,13 +4,12 @@
 
 * `git clone <repository-url>`
 * `cd ember-test-waiters`
-* `yarn install`
+* `npm ci`
 
 ## Linting
 
-* `yarn lint:hbs`
-* `yarn lint:js`
-* `yarn lint:js --fix`
+* `npm run lint`
+* `npm run lint:fix`
 
 ## Running tests
 
@@ -23,4 +22,4 @@
 * `ember serve`
 * Visit the dummy application at [http://localhost:4200](http://localhost:4200).
 
-For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).
+For more information on using ember-cli, visit [https://ember-cli.com/](https://ember-cli.com/).