DOC: fix changelog cross-reference — use plain code instead of broken :func: role

check_version is not listed in doc/api/ so :func:`mne.utils.check_version`
fails the Sphinx docs build. Replace with plain inline ``check_version``.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: baris-talar

doc/changes/dev/13863.bugfix.rst

@@ -1,4 +1,4 @@
-:func:`mne.utils.check_version` now gracefully handles packages that do not
-expose ``__version__`` at the top level when no minimum version is required.
-This improves handling of optional dependencies in ``_soft_import``, by
+``check_version`` now gracefully handles packages that do not expose
+``__version__`` at the top level when no minimum version is required,
+improving handling of optional dependencies in ``_soft_import``, by
 :newcontrib:`Baris Talar`.