Add gogs hook to argocd-notifications-controller

[Dpoke]

Hello!

Please add gogs hook processing to argocd-notifications-controller.
Now If you use such hook type in argocd-notifications-controller (not in argocd-server), you get error 400 (with the next error message: Webhook processing failed: json: cannot unmarshal string into Go struct field .repository.created_at of type int64)

Useful discussion link here where people discussed topic with webhook processing in both argocd-notifications-controller and argocd-server.

As I see from code here and here, now argocd-notifications-controller can use only 3 types of hooks (gitlab, github, azuredevops) while argocd-server can use more types (azuredevops, bitbucket, github, gitlab, gogs)

I think it will be a good idea to make webhook processing the same in both applications.