Merge pull request #3118 from crazy-max/dockerfile-buildkit-0.21.0

dockerfile: update buildkit to 0.21.0

Author: crazy-max

Dockerfile

@@ -11,7 +11,7 @@ ARG DOCKER_VERSION_ALT_26=26.1.3
 ARG DOCKER_CLI_VERSION=${DOCKER_VERSION}
 ARG GOTESTSUM_VERSION=v1.12.0
 ARG REGISTRY_VERSION=3.0.0
-ARG BUILDKIT_VERSION=v0.20.2
+ARG BUILDKIT_VERSION=v0.21.0
 ARG UNDOCK_VERSION=0.9.0
 
 FROM --platform=$BUILDPLATFORM tonistiigi/xx:${XX_VERSION} AS xx