Merge pull request #1165 from vvoland/update-buildx

[master] Bump buildx to v0.21.0-rc2

Author: vvoland

common.mk

@@ -43,7 +43,7 @@ DOCKER_ENGINE_REF  ?= $(REF)
 DOCKER_COMPOSE_REF ?= v2.33.0
 # DOCKER_BUILDX_REF is the version of compose to package. It usually is a tag,
 # but can be a valid git reference in DOCKER_BUILDX_REPO.
-DOCKER_BUILDX_REF  ?= v0.20.1
+DOCKER_BUILDX_REF  ?= v0.21.0-rc2
 
 # Use "stage" to install dependencies from download-stage.docker.com during the
 # verify step. Leave empty or use any other value to install from download.docker.com