not requires a whitespace

[jods4]

According to Oasis ABNF for OData, not operator must be followed by RWS, a.k.a. a required whitespace.
The library puts no space between not and the following brackets ().
This is a super easy fix, just add a space here:
https://github.com/techniq/odata-query/blob/master/src/index.ts#L567-L569