pygolang: v↑ (0.0.8 -> 0.0.9)

This upgrade fixes deadlock when new context is created from
already-canceled parent[1]. It also comes with other minor enhancements
and fixes needed e.g. for `zodb restore`[2].

[1] nexedi/pygolang@58d4cbfe
[2] https://pypi.org/project/pygolang/#pygolang-change-history