Revert "Support npm >= 7 (#658)" (#662)

This reverts commit 5d35a0e.

Author: dxvladislavvolkov

.github/workflows/tests.yml

@@ -26,7 +26,7 @@ jobs:
     - name: Clone devextreme repo
       run: test -d ../devextreme || git clone -b 22_1 https://github.com/devexpress/devextreme ../devextreme
 
-    - name: Use Node.js 16
+    - name: Use Node.js 15
       uses: actions/setup-node@v2
       with:
         node-version: '15'
@@ -39,11 +39,18 @@ jobs:
       run: |
         cd ../devextreme
         npm run build-dist
-
+    - name: Use Node.js 14
+      uses: actions/setup-node@v2
+      with:
+        node-version: '14'
     - name: Install devextreme package
       run: |
-        npx lerna add devextreme@file:../devextreme/artifacts/npm/devextreme/ --dev --no-bootstrap --scope=devextreme-react --exact
-        npx lerna add devextreme@file:../devextreme/artifacts/npm/devextreme/ --dev --no-bootstrap --scope=devextreme-react-sandbox --exact
+        cd ./packages/devextreme-react
+        npm install --save-dev ../../../devextreme/artifacts/npm/devextreme
+        cd ../sandbox
+        npm install --save-dev ../../../devextreme/artifacts/npm/devextreme
+        cd ../../
+        npm install --save-dev ../devextreme/artifacts/npm/devextreme
 
     - name: Run npm install
       run: npm install --no-audit --no-fund