Update sailfishos-chum-gui.changes and bump version to 0.5.0

[Olf0]

See https://github.com/sailfishos-chum/sailfishos-chum-gui/releases/tag/v0.4.1 and https://github.com/sailfishos-chum/sailfishos-chum-gui/compare/v0.4.1...v0.5.0

[Olf0]

I did successfully test v0.4.1+main.20220226… and its prior test-version v0.4.1+main.20220221… on SFOS 3.2.1 and 4.0.1.

This PR is just a suggestion, but I believe that enough changes were accumulated to increase the minor version (not the micro- / patchlevel-version), some changes also slightly change behaviour (hence it is not a bugfix release), and the current changes should be exposed to a greater audience for testing, before further changes are implemented on top of them.

[Olf0]

Suggestions for tagging, release title and description:

• Git-tag name (tags should be version numbers to be easily used, hence suggesting to drop the prefixed "v"): 0.5.0
• Release title: v0.5.0
• Description (taken from the changes file):

  Changes

• Rework strings
• Update translations
• Use generic type for SFOS older than 4.1
• Enhance spec file
• Fallback to tag info if release is not described at GitHub
• Disable package operations while there is some operation running
• Remove the search box focus when scrolling

[rinigus]

I was in the middle of generation the release already. But as you generated full changelog, will try to merge it. Hopefully there will be no conflicts