gdb: run black code formatter on gdbarch_components.py

The following commit changed gdbarch_components.py but failed to
format it with black:

  commit cf141dd8
  Date:   Wed Feb 22 12:15:34 2023 +0000

      gdb: fix reg corruption from displaced stepping on amd64

This commit just runs black on the file and commits the result.

The change is just the addition of an extra "," -- there will be no
change to the generated source files after this commit.

There will be no user visible changes after this commit.