remove strict_optional from sample mypy.ini in doc
Really not critical, but strict_optional=True is the default for mypy since 0.600, so its presence in the sample mypy.ini in the docs seems redundant.
@@ -123,7 +123,6 @@ A `mypy.ini` file with all plugin strictness flags enabled (and some other mypy
plugins = pydantic.mypy
follow_imports = silent
-strict_optional = True
warn_redundant_casts = True
warn_unused_ignores = True
disallow_any_generics = True
