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See merge request !5

Update go.mod, fix build

See merge request !4

Add go.mod

See merge request !3

This reverts commit 367541d4.

Fix project URL reference

See merge request !2

Add CI

Closes #5

See merge request !1

* Allow to be skipped if used with an ISP that doesn't provide IPv6
* Support reducing to prefix if running multiple instances; otherwise, instance portion of IPv6 address causes excessive updating

Fixes #1