Advance e2e test matrix (remove v1.28 and add v1.31).

Author: jkh52

.github/workflows/e2e.yaml

@@ -62,7 +62,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        k8s: [ v1.28.7, v1.29.2, v1.30.4 ]
+        k8s: [ v1.29.13, v1.30.9, v1.31.5 ]
         connection-mode: [ grpc, http-connect ]
     steps:
     - name: Install kind