[build] upgrade to Prettier 3.6.2 (#86)

Upgrades Prettier to 3.6.2 and pins it there. Prettier [recommends pinning the version](https://prettier.io/docs/install#summary):

> Install an exact version of Prettier locally in your project. This makes sure that everyone in the project gets the exact same version of Prettier. Even a patch release of Prettier can result in slightly different formatting, so you wouldn’t want different team members using different versions and formatting each other’s changes back and forth.

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Should probably merge after #85.

Co-authored-by: tobi <kipvandenbos@noreply.codeberg.org>
Reviewed-on: https://codeberg.org/superseriousbusiness/masto-fe-standalone/pulls/86
Co-authored-by: Zoë Bijl <code@moiety.me>
Co-committed-by: Zoë Bijl <code@moiety.me>

package.json

@@ -208,7 +208,7 @@
     "jest": "^29.5.0",
     "jest-environment-jsdom": "^29.5.0",
     "lint-staged": "^13.2.2",
-    "prettier": "^3.0.0",
+    "prettier": "3.6.2",
     "react-test-renderer": "^18.2.0",
     "stylelint": "^15.10.1",
     "stylelint-config-standard-scss": "^11.0.0",