net/ooni-mini: update 0.16.0 to 0.18.0

while here, also:
  - update dependencies (go modules);
  - update golang's libs;
  - update "utls" lib from yawning's obfs4proxy-0.0.11 branch (GitLab);
  - update core dependency, goptlib [1].

[1]
lists.torproject.org/pipermail/anti-censorship-team/2020-September/000122.html

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