[BUG] `optionaltrue` appended to entries from pyproject.toml

[xylar]

A recent change in grayskull seems to now be producing lines like:

- crate >=0.30.1,<1optionaltrue

For optional entries in a pyproject.toml, e.g.: https://github.com/earthobservations/wetterdienst/blob/v0.70.0/pyproject.toml#L136

See: https://github.com/conda-forge/wetterdienst-feedstock/pull/115/commits/a22fa2b0a36be509fe061a2016e6da67d95130b7