triage: upgrade to python3
triage: upgrade to python3

ci-test-infra-triage job is failing with:

```bash
 ImportError: No module named enum
```

https://storage.googleapis.com/kubernetes-jenkins/logs/ci-test-infra-triage/1573399794209001472/build-log.txt

Bumping python to v3 expecting we can get missing python package.

Signed-off-by: Arnaud Meukam <96190fcd0798f0afa72279990e31ddc33e4f2ea2@gmail.com>

kubernetes/test-infra,cjwagner/test-infra,kubernetes/test-infra,BenTheElder/test-infra,BenTheElder/test-infra,michelle192837/test-infra,BenTheElder/test-infra,cjwagner/test-infra,cblecker/test-infra,BenTheElder/test-infra,jessfraz/test-infra,cblecker/test-infra,jessfraz/test-infra,dims/test-infra,kubernetes/test-infra,cblecker/test-infra,michelle192837/test-infra,cjwagner/test-infra,BenTheElder/test-infra,kubernetes/test-infra,cblecker/test-infra,jessfraz/test-infra,michelle192837/test-infra,cjwagner/test-infra,BenTheElder/test-infra,dims/test-infra,kubernetes/test-infra,cjwagner/test-infra,michelle192837/test-infra,cblecker/test-infra,jessfraz/test-infra,dims/test-infra,jessfraz/test-infra,dims/test-infra,kubernetes/test-infra,michelle192837/test-infra,cblecker/test-infra,cjwagner/test-infra,dims/test-infra,michelle192837/test-infra,dims/test-infra,jessfraz/test-infra