Fix: Handle a list of keys (not just a single key) in Django cache sp…

…ans (#2082)

* Just adding the first argument (the key/keys) makes live much easier.

sentry_sdk/integrations/django/caching.py

@@ -31,7 +31,7 @@ def _instrument_call(cache, method_name, original_method, args, kwargs):
         if integration is None or not integration.cache_spans:
             return original_method(*args, **kwargs)
 
-        description = "{} {}".format(method_name, " ".join(args))
+        description = "{} {}".format(method_name, args[0])
 
         with hub.start_span(op=OP.CACHE, description=description) as span:
             value = original_method(*args, **kwargs)