chore: upgrade to Go 1.25

ref: https://issues.redhat.com/browse/ACM-27466
Signed-off-by: Dale Haiducek <[email protected]>

Author: dhaiducek

.ci-operator.yaml

@@ -1,4 +1,4 @@
 build_root_image:
   name: builder
   namespace: stolostron
-  tag: go1.24-linux
+  tag: go1.25-linux

go.mod

@@ -1,6 +1,6 @@
 module open-cluster-management.io/policy-generator-plugin
 
-go 1.24.0
+go 1.25.0
 
 require (
 	github.com/google/go-cmp v0.7.0