gdb: re-format Python files with black 24.1.1

New year, new black version.

Change-Id: I664601e6dd255358063e15f6d73bc5f02c8f2b9d

gdb/python/lib/gdb/FrameDecorator.py

@@ -251,7 +251,6 @@ class SymValueWrapper(object):
 
 
 class FrameVars(object):
-
     """Utility class to fetch and store frame local variables, or
     frame arguments."""
 

gdb/python/lib/gdb/command/prompt.py

@@ -21,7 +21,6 @@ import gdb.prompt
 
 
 class _ExtendedPrompt(gdb.Parameter):
-
     """Set the extended prompt.
 
     Usage: set extended-prompt VALUE