Use specific version of woodpeckerci/plugin-docker-buildx

.woodpecker.yaml

@@ -9,7 +9,7 @@ variables:
 
 steps:
   dryrun:
-    image: woodpeckerci/plugin-docker-buildx
+    image: woodpeckerci/plugin-docker-buildx:5.1.0
     settings:
       dockerfile: *file
       platforms: linux/arm64/v8,linux/amd64
@@ -21,7 +21,7 @@ steps:
       path: *file
 
   publish:
-    image: woodpeckerci/plugin-docker-buildx
+    image: woodpeckerci/plugin-docker-buildx:5.1.0
     settings:
       dockerfile: *file
       platforms: linux/arm64/v8,linux/amd64