Add CI to ensure links to downloads in Readme are not outdated

[RubenKelevra]

The current downloads listed in the install section of the readme are version 0.17 while the current version is 0.18.1.

I think we should not link specific versions here, but link to the release list on Github.

[lidel]

Updated links to 0.19.3. Sadly, releases page on its own is not enough - no way to show platform-specific installer, and users are confused which one to use download (especially on macOS, where we have .zip for autoupdate mechanism).

Keeping this open to add automation that does this version bump in README automatically, or generate "Install" section in release notes somehow.