Type check SHA response

[adamrdrew]

This patch adds a type check on the response object when we get a SHA. it can sometimes be a list rather than a dict.

We got this report and this should fix it:

2023-08-24 14:22:41 [   ERROR] [          MainThread] failed to fetch template file for service-accounts
2023-08-24 14:22:41 [   ERROR] [          MainThread] hit fatal error: list indices must be integers or slices, not str
2023-08-24 14:22:41 [    INFO] [          MainThread] releasing namespace 'ephemeral-x0cun8'
2023-08-24 14:22:42 [    INFO] [          MainThread] processing namespace reservation
2023-08-24 14:22:42 [    INFO] [          MainThread] running (pid 95686): oc apply -f -
2023-08-24 14:22:43 [    INFO] [           pid-95686]  |stdout| namespacereservation.cloud.redhat.com/bonfire-reservation-cf86f0d8 configured
2023-08-24 14:22:43 [    INFO] [          MainThread] releasing reservation 'bonfire-reservation-cf86f0d8' namespace 'ephemeral-x0cun8'
ERROR: deploy failed: list indices must be integers or slices, not str

[bsquizz]

Unclear how we got a list back, since API docs don't indicate that we should get a list: https://docs.github.com/en/rest/git/refs?apiVersion=2022-11-28#get-a-reference -- but at any rate, LGTM.