Automatically update installations on Windows and macOS
Following up on #2584 (closed), it would make sense to simplify updating GIMP on Windows/macOS to further bring down reports against obsolete versions of GIMP and deal with our brown paper bag releases (re. updated installers).
One commonly used framework for that is Sparkle.
macOS: https://sparkle-project.org/
Windows: https://winsparkle.org/