Make asset library template not a dotfile

The old path was the default filename for the action we are using but I
don't think this file should be a dotfile: it's part of the build
system, and is a file we might reasonably want to modify periodically.

https://phabricator.endlessm.com/T35503

Author: wjt

.github/workflows/godot-asset-library.yaml

@@ -18,3 +18,4 @@ jobs:
           username: ${{ secrets.GODOT_ASSET_LIBRARY_USERNAME }}
           password: ${{ secrets.GODOT_ASSET_LIBRARY_PASSWORD }}
           assetId: 3095
+          assetTemplate: asset-template.json.hb