Remove engines from package.json

The intention was to enforce developers of the project to use a minimal version
of yarn. However, the yarn and npm engines determine which version of those
package managers may be used to install `yaml-language-server`. This caused
warnings for users using npm or older yarn versions.

The node engines field signals required node version that’s needed. Setting it
to `*` is equivalent to not setting it at all.

Closes #521

Author: remcohaszing

package.json

@@ -17,11 +17,6 @@
       "name": "Google LLC"
     }
   ],
-  "engines": {
-    "node": "*",
-    "npm": "\n\nERROR: Please use yarn, npm is not supported in this repository!!!\n\n",
-    "yarn": "^1.22.5"
-  },
   "bin": {
     "yaml-language-server": "./bin/yaml-language-server"
   },