flake8: fix warnings for unused imports
This is supposed to expose all primitives together, but to do that we
need to actually "use" each variable in `__all__`, which we... didn't.
Sorry about that.
@@ -12,6 +12,8 @@ __all__ = [
'MesonVersionStringHolder',
'DependencyVariableString',
'DependencyVariableStringHolder',
+ 'OptionString',
+ 'OptionStringHolder',
]
from .array import ArrayHolder
