FTBFS, python 3.12

Description:

As imp module was removed in python 3.12, this package fails to build

==> Starting build()...
Building instrumented JS...
/build/js91/src/firefox-91.13.0/./mach:12: SyntaxWarning: invalid escape sequence '\ '
  ''':'
Traceback (most recent call last):
  File "/build/js91/src/firefox-91.13.0/./mach", line 171, in <module>
    main(sys.argv[1:])
  File "/build/js91/src/firefox-91.13.0/./mach", line 163, in main
    mach = check_and_get_mach(os.path.dirname(os.path.realpath(__file__)))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/js91/src/firefox-91.13.0/./mach", line 150, in check_and_get_mach
    return load_mach(dir_path, mach_path)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/js91/src/firefox-91.13.0/./mach", line 138, in load_mach
    return mach_bootstrap.bootstrap(dir_path)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/js91/src/firefox-91.13.0/build/mach_bootstrap.py", line 205, in bootstrap
    import mach.main
  File "/build/js91/src/firefox-91.13.0/python/mach/mach/main.py", line 13, in <module>
    import imp
ModuleNotFoundError: No module named 'imp'
==> ERROR: A failure occurred in build().
    Aborting...