Bump buildx in pipeline to the recent version (#40)

Signed-off-by: Yury Tsarev <yury@upbound.io>

Author: ytsarev

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ env:
   # Common versions
   GO_VERSION: '1.25.5'
   GOLANGCI_VERSION: 'v2.8.0'
-  DOCKER_BUILDX_VERSION: 'v0.23.0'
+  DOCKER_BUILDX_VERSION: 'v0.30.1'
 
   # These environment variables are important to the Crossplane CLI install.sh
   # script. They determine what version it installs.