Bump optional dependency prettier version to version range to prevent version conflicts with other packages

[sceee]

Is your enhancement related to a problem? Please describe.

yaml-language-server declares a specific 2.8.7 version of prettier as optional dependency:

yaml-language-server/package.json

Line 33 in f039273

"prettier": "2.8.7"

This causes issues with different prettier versions being installed in a project / being used by other packages.
E.g. with astro:

└─┬ @astrojs/[email protected]
  └─┬ @astrojs/[email protected]
    ├── [email protected] invalid: "^3.0.0" from node_modules/@astrojs/language-server
    ├─┬ [email protected]
    │ └── [email protected] deduped invalid: "^3.0.0" from node_modules/@astrojs/language-server
    └─┬ [email protected]
      └─┬ [email protected]
        └── [email protected] deduped invalid: "^3.0.0" from node_modules/@astrojs/language-server

npm error code ELSPROBLEMS
npm error invalid: [email protected] C:\my_proj\node_modules\prettier

Describe the solution you would like

Either remove prettier as optional dependency or declare a version range like ">=2.8.7" for the optional prettier dependency so that it can correctly be deduped by npm depending on the other version constaints from the project / other dependencies.

Describe alternatives you have considered

Overriding the prettier version yaml-language-server declares in my project's package.json via:

"overrides": {
    "yaml-language-server": {
      "prettier": ">=2.8.7"
    }
  }

...to "hack" around the problem.

Additional context

Related to #909 which has been open since a long time but there was no longer any activity.