Adapt release defaults

Author: thardeck

.github/workflows/release-against-rancher.yml

@@ -3,15 +3,15 @@ on:
   workflow_dispatch:
     inputs:
       rancher_ref:
-        description: "Submit PR against the following rancher/rancher branch (e.g. release/v2.13 or main if there is no according release branch yet)"
+        description: "Submit PR against the following rancher/rancher branch (e.g. release/v2.15 or main if there is no according release branch yet)"
         required: true
-        default: "main"
+        default: "release/v0.15"
       new_fleet:
-        description: "New Fleet version (e.g. 0.14.0-rc.1)"
+        description: "New Fleet version (e.g. 0.15.0-rc.1)"
         required: true
         default: ""
       new_chart:
-        description: "New Rancher Chart version (e.g. 108.0.0)"
+        description: "New Rancher Chart version (e.g. 109.0.0)"
         required: true
         default: ""
       should_bump_api: