Golang minimum version is 1.13 and not 1.11

[meepmeep]

Documentation says that golang 1.11 or later is need, but when trying to build on my server I got this error :

go build golang.org/x/text/unicode/norm: /usr/lib/go-1.11/pkg/tool/linux_amd64/compile: signal: killed
go build golang.org/x/text/encoding/japanese: /usr/lib/go-1.11/pkg/tool/linux_amd64/compile: signal: killed
go build golang.org/x/text/encoding/simplifiedchinese: /usr/lib/go-1.11/pkg/tool/linux_amd64/compile: signal: killed
# github.com/kiwiirc/webircgateway/pkg/dnsbl
pkg/dnsbl/dnsbl.go:55:16: undefined: strings.ReplaceAll
note: module requires Go 1.13

Please update the documentation ;)