chore(mypy[overrides]): Add sphinx_fonts to ignore_missing_imports

why: mypy reports `import-not-found` for `sphinx_fonts` since the package
does not ship type stubs or a py.typed marker.
what:
- Add "sphinx_fonts" to the [[tool.mypy.overrides]] module list
- Position it alongside other Sphinx extension ignores

Author: tony

pyproject.toml

@@ -142,6 +142,7 @@ exclude = [
 
 [[tool.mypy.overrides]]
 module = [
+  "sphinx_fonts",
   "cli_usage_lexer",
   "argparse_lexer",
   "argparse_roles",