Rename INI val stripe_api_key to ini_keys.stripe

This will be a bit more organized when I start adding in some other API
keys.

tildes/production.ini.example

@@ -20,8 +20,6 @@ redis.sessions.timeout = 3600
 
 sqlalchemy.url = postgresql+psycopg2://tildes:@:6432/tildes
 
-stripe_api_key = sk_live_ActualKeyShouldGoHere
-
 tildes.welcome_message_sender = Deimos
 
 webassets.auto_build = false
@@ -30,6 +28,9 @@ webassets.base_url = /
 webassets.cache = false
 webassets.manifest = json
 
+# API keys for external APIs
+api_keys.stripe = sk_live_ActualKeyShouldGoHere
+
 [server:main]
 use = egg:gunicorn#main
 bind = unix:/run/gunicorn/socket

tildes/tildes/views/donate.py

@@ -30,7 +30,7 @@ def post_donate_stripe(
 ) -> dict:
     """Process a Stripe donation."""
     try:
-        stripe.api_key = request.registry.settings["stripe_api_key"]
+        stripe.api_key = request.registry.settings["api_keys.stripe"]
     except KeyError:
         raise HTTPInternalServerError