pyproject(mypy): add sphinx_fonts to ignore_missing_imports

why: sphinx_fonts is a local docs/_ext extension, not an installed
package — mypy cannot resolve it at analysis time.
what:
- Add sphinx_fonts to [[tool.mypy.overrides]] ignore_missing_imports

Author: tony

pyproject.toml

@@ -161,6 +161,7 @@ module = [
   "shtab",
   "sphinx_argparse_neo",
   "sphinx_argparse_neo.*",
+  "sphinx_fonts",
   "cli_usage_lexer",
   "argparse_lexer",
   "argparse_roles",