doc/Troubleshooting: remove macOS GUI item

With #23 being fixed, it is probably not relevant anymore.

If someone reports that the default (legacy) UI does not work on macOS
for them, but the ImageJ2 Swing UI does, we can reintroduce something.

doc/Troubleshooting.md

@@ -99,23 +99,6 @@ imp = ij.py.WindowManager.getCurrentImage()
 ij.py.synchronize_ij1_to_ij2(imp)
 ```
 
-## The GUI has issues on macOS
-
-The default UI may not work on macOS. You can try using ImageJ's
-Swing-UI-based GUI instead by initializing with:
-
-```python
-import imagej
-ij = imagej.init(..., headless=False)
-ij.ui().showUI("swing")
-```
-
-Replacing `...` with one of the usual possibilities
-(see [Initialization.md](Initialization.md)).
-
-See [this thread](https://github.com/imagej/pyimagej/issues/23)
-for additional information and updates.
-
 ## Original ImageJ classes not found
 
 If you try to load an original ImageJ class (with package prefix `ij`),