Revert "Increase npm version to 7.9 (#2466)"

This reverts commit 7970b11fe7.

package.json

@@ -203,7 +203,7 @@
     "moment": "^2.26.0",
     "moment-timezone": "^0.5.33",
     "node-pty": "^0.9.0",
-    "npm": "7.9",
+    "npm": "^6.14.8",
     "openid-client": "^3.15.2",
     "p-limit": "^3.1.0",
     "path-to-regexp": "^6.1.0",