textproc/py-pikepdf: Update to 1.16.1

• Add JBIG2 option as support for extracting JBIG2 images was introduced with the 1.16.0 release.

Changelog since 1.14.0:

https://github.com/pikepdf/pikepdf/blob/v1.16.1/docs/release_notes.rst

MFH: 2020Q3 (blanket: bug/regression fixes)