fix(type): remove ClassVar from Directive.option_spec override

ty flags option_spec: ClassVar as an invalid class-variable override of
Directive.option_spec which is an instance variable in docutils.

Author: gaborbernat

docs/tox_conf.py

@@ -10,6 +10,8 @@
 from sphinx.util.logging import getLogger
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
     from docutils.parsers.rst.states import RSTState, RSTStateMachine
     from sphinx.domains.std import StandardDomain
 
@@ -19,7 +21,7 @@
 class ToxConfig(SphinxDirective):
     name = "conf"
     has_content = True
-    option_spec: ClassVar[dict[str, Any]] = {
+    option_spec: ClassVar[dict[str, Callable[[str], Any]]] = {
         "keys": unchanged_required,
         "version_added": unchanged,
         "version_deprecated": unchanged,