core/endpoint: Get choices from PUT if POST missing

If the API token is not allowed to POST on a particular endpoint, choices won't
be returned in `.actions.POST`, but we can still get them in `.actions.PUT`.

This commit falls back to getting choices from `.actions.PUT` instead of
raising an exception when `.actions.POST` is missing.

pynetbox/core/endpoint.py

@@ -585,9 +585,10 @@ def choices(self):
             token=self.api.token,
             http_session=self.api.http_session,
         ).options()
-        try:
-            post_data = req["actions"]["POST"]
-        except KeyError:
+
+        actions = req.get("actions", {})
+        post_data = actions.get("POST") or actions.get("PUT")
+        if post_data is None:
             raise ValueError(
                 "Unexpected format in the OPTIONS response at {}".format(self.url)
             )