.pullapprove.yml: Change "image-spec-maintainers" -> "image-tools-maintainers"

Now that this is an independent project.

Signed-off-by: W. Trevor King <[email protected]>

Author: wking

.pullapprove.yml

@@ -6,6 +6,6 @@ signed_off_by:
   required: true
 reviewers:
   teams:
-  - image-spec-maintainers
+  - image-tools-maintainers
   name: default
   required: 2