[LyX/master] Set Box label color to static black.

[Juergen Spitzmueller]

commit 9119671ee69edbe0efe983056bc0b1543afcb500
Author: Juergen Spitzmueller <spitz at lyx.org>
Date:   Mon Sep 18 07:29:02 2023 +0200

    Set Box label color to static black.
    
    Foreground in dark mode does not have enough contrast against the label
    background
---
 lib/layouts/stdinsets.inc |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/lib/layouts/stdinsets.inc b/lib/layouts/stdinsets.inc
index 865b5ec..6fab49c 100644
--- a/lib/layouts/stdinsets.inc
+++ b/lib/layouts/stdinsets.inc
@@ -469,7 +469,7 @@ End
 InsetLayout Box
 	InheritFont           false
 	LabelFont
-	  Color               foreground
+	  Color               black
 	  Size                Small
 	EndFont
 	MultiPar              true