Caddy: undefined: tls.VersionTLS13

[greenpau]

Build fails:

INFO: started caddy setup ...
git version 1.8.3.1
+ cd /root/dev/go/src/github.com/mholt/caddy/caddy/
+ cd /root/dev/go/src/github.com/mholt/caddy/caddy
+ PROJECT=github.com/mholt/caddy
++ git describe
+ PROJECT_VERSION=v0.11.4-8-g72d0deb
+ CGO_ENABLED=0
+ go build -v -o ./caddy '-ldflags=-w -s   -X github.com/mholt/caddy/caddy/caddymain.gitTag=v0.11.4-8-g72d0deb' -gcflags=all=-trimpath=/root/dev/go/src -asmflags=all=-trimpath=/root/dev/go/src ./main.go
github.com/mholt/caddy/caddytls
# github.com/mholt/caddy/caddytls
../caddytls/config.go:410:31: undefined: tls.VersionTLS13
../caddytls/config.go:433:12: undefined: tls.VersionTLS13

[francislavoie]

Go 1.12 is now a requirement to build from master. See https://github.com/mholt/caddy/issues/2080#issuecomment-467257488