SG-40910 Fix banner text contrast on macOS in Adobe apps (#132)

* Fix banner text contrast on macOS in Adobe apps

The banner info message displayed at the top of the Loader after
triggering actions (e.g., "Open File") had poor contrast on macOS,
especially in Photoshop and After Effects. The text appeared in beige
color on a blue background, making it nearly unreadable.

The issue was caused by using palette().text() for the text color,
which is designed for use on the base background color, not on a
highlight background.

Changed to use palette().highlightedText() instead, which is
specifically designed for text displayed on highlight-colored
backgrounds, ensuring proper contrast across all platforms and
applications.

Fixes text readability in banner messages on macOS in Adobe DCCs.

Author: julien-lang

python/tk_multi_loader/banner.py

@@ -39,7 +39,7 @@ def __init__(self, parent):
             border-bottom-right-radius: 10px;
         """.format(
                 highlight=self.palette().highlight().color().name(),
-                text=self.palette().text().color().name(),
+                text=self.palette().highlightedText().color().name(),
             )
         )