deck: Fix off-by-one overflow when jobs are older than 48h
deck: Fix off-by-one overflow when jobs are older than 48h

If the prow list contained a job older than 48h (which it didn't a few
hours ago, but does now) then the page would error.

kubernetes/test-infra,ixdy/kubernetes-test-infra,brahmaroutu/test-infra,pwittrock/test-infra,pwittrock/test-infra,krzyzacy/test-infra,dims/test-infra,jessfraz/test-infra,lavalamp/test-infra,fejta/test-infra,jessfraz/test-infra,cblecker/test-infra,monopole/test-infra,cblecker/test-infra,BenTheElder/test-infra,michelle192837/test-infra,jessfraz/test-infra,dims/test-infra,kubernetes/test-infra,cjwagner/test-infra,brahmaroutu/test-infra,dims/test-infra,BenTheElder/test-infra,krzyzacy/test-infra,fejta/test-infra,michelle192837/test-infra,BenTheElder/test-infra,lavalamp/test-infra,cjwagner/test-infra,lavalamp/test-infra,ixdy/kubernetes-test-infra,brahmaroutu/test-infra,kubernetes/test-infra,cblecker/test-infra,pwittrock/test-infra,kubernetes/test-infra,monopole/test-infra,cjwagner/test-infra,cblecker/test-infra,kubernetes/test-infra,pwittrock/test-infra,krzyzacy/test-infra,monopole/test-infra,fejta/test-infra,ixdy/kubernetes-test-infra,lavalamp/test-infra,kubernetes/test-infra,cblecker/test-infra,brahmaroutu/test-infra,ixdy/kubernetes-test-infra,lavalamp/test-infra,jessfraz/test-infra,lavalamp/test-infra,cjwagner/test-infra,jessfraz/test-infra,dims/test-infra,cblecker/test-infra,krzyzacy/test-infra,michelle192837/test-infra,monopole/test-infra,krzyzacy/test-infra,michelle192837/test-infra,fejta/test-infra,michelle192837/test-infra,cjwagner/test-infra,monopole/test-infra,brahmaroutu/test-infra,dims/test-infra,fejta/test-infra,jessfraz/test-infra,michelle192837/test-infra,krzyzacy/test-infra,dims/test-infra,BenTheElder/test-infra,BenTheElder/test-infra,pwittrock/test-infra,BenTheElder/test-infra,brahmaroutu/test-infra,monopole/test-infra,ixdy/kubernetes-test-infra,fejta/test-infra,cjwagner/test-infra