Include caching in docker deploy

.github/workflows/docker_deploy.yml

@@ -53,4 +53,6 @@ jobs:
           platforms: linux/amd64,linux/arm64
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=registry,ref=mcranmer/pysr:buildcache
+          cache-to: type=registry,ref=mcranmer/pysr:buildcache,mode=max