builder-next: fix buildkit version

Update the version manually (we don't have automation for this yet), and
add a comment to vendor.mod to help users remind to update it.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

builder/builder-next/worker/worker.go

@@ -50,7 +50,7 @@ import (
 )
 
 func init() {
-	version.Version = "v0.11.0-rc3"
+	version.Version = "v0.11.5"
 }
 
 const labelCreatedAt = "buildkit/createdat"

vendor.mod

@@ -56,7 +56,7 @@ require (
 	github.com/klauspost/compress v1.16.3
 	github.com/miekg/dns v1.1.43
 	github.com/mistifyio/go-zfs v2.1.2-0.20190413222219-f784269be439+incompatible
-	github.com/moby/buildkit v0.11.5
+	github.com/moby/buildkit v0.11.5 // IMPORTANT: when updating, also update the version in builder/builder-next/worker/worker.go
 	github.com/moby/ipvs v1.1.0
 	github.com/moby/locker v1.0.1
 	github.com/moby/patternmatcher v0.5.0