Fix the visibility of the license target in TFF.

PiperOrigin-RevId: 630442675

BUILD

@@ -2,7 +2,7 @@ load("@rules_license//rules:license.bzl", "license")
 
 package(
     default_applicable_licenses = [":package_license"],
-    default_visibility = ["//visibility:private"],
+    default_visibility = ["//visibility:public"],
 )
 
 license(