Merge branch 'upgrade-ai3-go-common' into 'master'

go.mod

go.sum

vendor/git.autistici.org/ai3/go-common/.gitlab-ci.yml

vendor/git.autistici.org/ai3/go-common/go.mod

vendor/git.autistici.org/ai3/go-common/go.sum

vendor/github.com/NYTimes/gziphandler/go.mod

vendor/github.com/NYTimes/gziphandler/go.sum

vendor/github.com/cenkalti/backoff/v4/.travis.yml

vendor/github.com/cenkalti/backoff/v4/README.md

vendor/github.com/cenkalti/backoff/v4/exponential.go

vendor/github.com/cenkalti/backoff/v4/go.mod

vendor/github.com/cenkalti/backoff/v4/retry.go

vendor/github.com/cespare/xxhash/v2/README.md

vendor/github.com/cespare/xxhash/v2/go.mod

vendor/github.com/cespare/xxhash/v2/testall.sh

vendor/github.com/cespare/xxhash/v2/xxhash.go

vendor/github.com/cespare/xxhash/v2/xxhash_amd64.s

vendor/github.com/cespare/xxhash/v2/xxhash_arm64.s

vendor/github.com/cespare/xxhash/v2/xxhash_asm.go

vendor/github.com/cespare/xxhash/v2/xxhash_other.go