Update Saber repo

Required

• The app complies with the inclusion criteria
• All related fdroiddata and RFP issues have been referenced in this merge request
• Builds with fdroid build

Strongly Recommended

• The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure
• Releases are tagged

Suggested

• External repos are added as git submodules instead of srclibs
• Multiple apks for native code

Description

This MR updates the repo from https://github.com/adil192/saber to https://github.com/saber-notes/saber. Note that the old link redirects to the new one but it's recommended to update the link.