pygolang: v↑ (0.0.9 -> 0.1)

This upgrade adds ability to handle signals via nogil channels, and
other improvements and fixes.

See nexedi/pygolang@e18adbab and
https://pypi.org/project/pygolang/#pygolang-change-history for details.

/reviewed-by @jerome
/reviewed-on nexedi/slapos!1120