[electron-update-server] Ignore older releases

Summary:
Fix for https://linear.app/comm/issue/ENG-4073
hazel (the update server for electron) has these issues:

• it depends on the ordering of releases returned by GitHub API, which isn't guaranteed
• it only checks if the new version from GitHub is different than the currently cached version

This diffs adds sorting of the results from github and checks if the new release is (semver) greater than the currently cached.

Test Plan:
Check with a test repo:

• add a new release, check if it's cached
• add a new release that has a lower semver, check that it's skipped

Reviewers: kamil, tomek

Reviewed By: kamil

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D8208