Remove engines from package.json
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

redhat-developer/yaml-language-server,redhat-developer/yaml-language-server