Fix ghcr.io buildx command in tag workflow

Author: benbusby

.github/workflows/buildx.yml

@@ -58,4 +58,4 @@ jobs:
             --platform linux/amd64,linux/arm64 .
           docker buildx build --push \
             --tag ghcr.io/benbusby/yeetfile:${GITHUB_REF#refs/*/v}\
-            --platform linux/amd64,linux/arm64
+            --platform linux/amd64,linux/arm64 .