Refactor subhub_api.yaml, payments.py: Update API response formatting

Updated references of 'nickname' to be 'plan_name' to allow for consistency in our responses

subhub/api/payments.py

@@ -211,7 +211,7 @@ def create_return_data(subscriptions) -> JsonDict:
                         "current_period_end": subscription["current_period_end"],
                         "current_period_start": subscription["current_period_start"],
                         "ended_at": subscription["ended_at"],
-                        "nickname": subscription["plan"]["nickname"],
+                        "plan_name": subscription["plan"]["nickname"],
                         "plan_id": subscription["plan"]["id"],
                         "status": subscription["status"],
                         "subscription_id": subscription["id"],
@@ -236,7 +236,7 @@ def create_subscription_object_without_failure(subscription: object) -> object:
         "current_period_end": subscription["current_period_end"],
         "current_period_start": subscription["current_period_start"],
         "ended_at": subscription["ended_at"],
-        "nickname": subscription["plan"]["nickname"],
+        "plan_name": subscription["plan"]["nickname"],
         "plan_id": subscription["plan"]["id"],
         "status": subscription["status"],
         "subscription_id": subscription["id"],
@@ -317,7 +317,7 @@ def create_update_data(customer) -> dict:
                         "current_period_end": subscription["current_period_end"],
                         "current_period_start": subscription["current_period_start"],
                         "ended_at": subscription["ended_at"],
-                        "nickname": subscription["plan"]["nickname"],
+                        "plan_name": subscription["plan"]["nickname"],
                         "plan_id": subscription["plan"]["id"],
                         "status": subscription["status"],
                         "subscription_id": subscription["id"],

subhub/subhub_api.yaml

@@ -363,7 +363,7 @@ definitions:
         currency:
           type: string
           example: usd
-        nickname:
+        plan_name:
           type: string
           example: Monthly Rocket Launches
   Subscriptions:
@@ -377,7 +377,7 @@ definitions:
         plan_id:
           type: string
           example: pro_basic_823
-        nickname:
+        plan_name:
           type: string
           example: "pro_basic"
         current_period_end: