[StatusPage] page_get_templates() wrong url

[rschre]

Currently the method page_get_templates of the StatusPage class raises an HTTP-error, no matter what you do.
I figure this is because of the line 1559 in statuspage.py where the url is defined as url = "v1/pages/{}/templates".format(page_id).

I managed to fix this for myself by changing the line to url = "v1/pages/{}/incident_templates".format(page_id).

[gonchik]

@rschre you're right. https://developer.statuspage.io/#operation/postPagesPageIdIncidentTemplates
I really appreciate for that feedback,