ci: switch to npm instead of yarn

Author: matthewjablack

.github/workflows/main.yml

@@ -15,9 +15,6 @@ jobs:
         with:
           node-version: 'lts/*'
 
-      - name: Setup Yarn
-        run: yarn set version 3.2.0
-
       - name: Cache Bitcoin node
         id: bitcoin-cache
         uses: actions/cache@v2
@@ -43,27 +40,27 @@ jobs:
         id: node-modules-cache
         uses: actions/cache@v2
         with:
-          key: ${{ runner.os }}-${{ hashFiles('yarn.lock') }}
+          key: ${{ runner.os }}-${{ hashFiles('package-lock.json') }}
           path: |
             node_modules
             */*/node_modules
 
       - name: Install dependencies
         if: steps.node-modules-cache.outputs.cache-hit != 'true'
-        run: yarn install --immutable
+        run: npm ci
 
       - name: Debug - List Processes
         run: ps aux
 
-      - run: yarn build
+      - run: npm run build
 
       - name: Debug - List Processes
         run: ps aux
 
       - name: Run tests with detailed output
         run: |
           echo "::group::Detailed Test Output"
-          yarn test
+          npm run test:integration:sequential
           echo "::endgroup::"
 
       - name: Get test coverage