ci(examples): name the Understone job distinctly

The job was named "test", colliding with core CI's "test" matrix so the PR
checks list showed two "test (3.11)" rows. Rename it to "understone" so the
example's checks read unambiguously (understone (3.11) / (3.13)).

(cherry picked from commit efa8664e4d)

.github/workflows/understone-example.yml

@@ -21,7 +21,7 @@ permissions:
   contents: read
 
 jobs:
-  test:
+  understone:
     runs-on: ubuntu-latest
     defaults:
       run: