Dockerfile: update buildx to v0.12.1

Update the version of buildx used in CI to the latest version.

- full diff: https://github.com/docker/buildx/compare/v0.12.0...v0.12.1
- release notes: https://github.com/docker/buildx/releases/tag/v0.12.1

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

Dockerfile

@@ -12,7 +12,7 @@ ARG DOCKERCLI_VERSION=v24.0.2
 # cli version used for integration-cli tests
 ARG DOCKERCLI_INTEGRATION_REPOSITORY="https://github.com/docker/cli.git"
 ARG DOCKERCLI_INTEGRATION_VERSION=v17.06.2-ce
-ARG BUILDX_VERSION=0.12.0
+ARG BUILDX_VERSION=0.12.1
 ARG COMPOSE_VERSION=v2.24.0
 
 ARG SYSTEMD="false"