ci: kata-deploy: Export KUBERNETES env var

So we have a better control on which flavour of kubernetes kata-deploy
is expected to be targetting.

This was also done as part of fa62a4c01b,
for the k8s tests.

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

.github/workflows/run-kata-deploy-tests-on-tdx.yaml

@@ -36,6 +36,7 @@ jobs:
       DOCKER_TAG: ${{ inputs.tag }}
       PR_NUMBER: ${{ inputs.pr-number }}
       KATA_HYPERVISOR: ${{ matrix.vmm }}
+      KUBERNETES: "k3s"
       USING_NFD: "true"
     steps:
       - uses: actions/checkout@v3