feat(releases): show current version of local installation via api

[NicolasNewman]

Motivation: When checking the newest release for a repository, it would be helpful to know which version you are using locally directly from the widget

Implementation:
Added additional optional fields:

• version-endpoint: the endpoint to fetch version information from
• version-path: the path to the version number using gjson syntax

Example:

repositories:
  - jellyfin/jellyfin
  - repository: go-vikunja/vikunja
    version-endpoint: https://vikunja.example/api/v1/info
    version-path: version
  - repository: rommapp/romm
    version-endpoint: https://romm.example/api/heartbeat
    version-path: SYSTEM.VERSION
  - repository: immich-app/immich
    version-endpoint: https://immich.example/api/server/about?apiKey=****
    version-path: version

TODO:

• Handle API authentication via headers/cookies