gh: ginkgo: reduce number of tested k8s versions in PRs

Seems like every time we bump the tested k8s versions, we accidentally
introduce a fourth version into the per-PR testing. But the established
pattern is actually to test on N, N-1 and N-3.

N-2 is still covered in the scheduled runs.

See 0c555f1 (".github: remove k8s 1.29 from testing per PR") for a
previous fix-up.

Fixes: e471a29 ("k8s: Add support for 1.32.0")
Signed-off-by: Julian Wiedmann <jwi@isovalent.com>

Author: julianwiedmann

.github/actions/ginkgo/main-prs.yaml

@@ -4,5 +4,4 @@
 k8s-version:
   - "1.34"
   - "1.33"
-  - "1.32"
   - "1.31"