Restrict npm version to v6 (#5950)

.npmrc

@@ -3,6 +3,10 @@
 # Config variables can be overridden by running:
 # npm run <script-name> --kubernetes-dashboard:<variable-name>=<value>
 
+# General configuration
+engine-strict = true
+
+# Dashboard configuration
 kubernetes-dashboard:kubeconfig_dir = ${HOME}/.kube
 kubernetes-dashboard:kubeconfig = ${HOME}/.kube/config
 kubernetes-dashboard:frontend_build_dir = dist/frontend/en

package.json

@@ -188,7 +188,7 @@
   },
   "engines": {
     "node": ">=10.13.0",
-    "npm": ">=6.0.0"
+    "npm": ">=6.0.0 <7.0.0"
   },
   "eslintConfig": {
     "parser": "@typescript-eslint/parser",