bump GHA e2e to use ubuntu-latest (20.04 is being removed 20250401)

Author: joelanford

.github/workflows/test.yml

@@ -11,7 +11,7 @@ on:
 
 jobs:
   e2e:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5