bug#58120: volctl missing gdk dependency?

[Simen Endsjø]

$ volctl 
Traceback (most recent call last):
  File 
"/gnu/store/phlappy7plp4gn2wm27f5bsp7wh9w9jd-volctl-0.8.2/bin/.volctl-real", 
line 33, in <module>
    sys.exit(load_entry_point('volctl==0.8.2', 'gui_scripts', 'volctl')())
  File 
"/gnu/store/phlappy7plp4gn2wm27f5bsp7wh9w9jd-volctl-0.8.2/bin/.volctl-real", 
line 25, in importlib_load_entry_point
    return next(matches).load()
  File 
"/gnu/store/zca340qfk43qys608q8pfwqqckll49qg-python-3.9.9/lib/python3.9/importlib/metadata.py",
 line 77, in load
    module = import_module(match.group('module'))
  File 
"/gnu/store/zca340qfk43qys608q8pfwqqckll49qg-python-3.9.9/lib/python3.9/importlib/__init__.py",
 line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File 
"/gnu/store/phlappy7plp4gn2wm27f5bsp7wh9w9jd-volctl-0.8.2/lib/python3.9/site-packages/volctl/__main__.py",
 line 9, in <module>
    gi.require_version("Gdk", "3.0")
  File 
"/gnu/store/ycbgix6sxahsr34553af7pkvj27rywqc-python-pygobject-3.40.1/lib/python3.9/site-packages/gi/__init__.py",
 line 126, in require_version
    raise ValueError('Namespace %s not available' % namespace)
ValueError: Namespace Gdk not available