Add Fedora Linux 43 Workstation to supported OSs

[mplieske]

I tested KeepTime with my Fedora Linux Workstation on version 43 with the following Amazon Corretto JDKs:

• 17
• 21
• 23
• 25

Building with tests worked on JDKs 17 - 23 but not on 25.
Building without tests worked on all tested JDKs.

The application worked for all JDKs.
Of course, as the build with tests didn't work with JDK 25, a quick test in the sense of using the application a bit, is not giving us any information.

As JDK 25 is just not supported by the Mockito version, I think it is fair to say, that we can add Fedora to the tested OSs on the README.

[mplieske]

I created PR #195 for this issue.