Update cross-env to version 7.0.0 (#5917)

package.json

@@ -91,7 +91,7 @@
     "@umijs/fabric": "2.0.0",
     "chalk": "^3.0.0",
     "check-prettier": "^1.0.3",
-    "cross-env": "^6.0.0",
+    "cross-env": "^7.0.0",
     "cross-port-killer": "^1.1.1",
     "enzyme": "^3.9.0",
     "express": "^4.17.1",