fix(spp_change_request_v2): use Datetime.now() for membership start_date

fields.Date.today() produces midnight UTC, which displays incorrectly
in non-UTC timezones. The membership start_date field is a Datetime, so
use fields.Datetime.now() to record the actual time the member was added.

Author: jeremi

spp_change_request_v2/strategies/add_member.py

@@ -54,7 +54,7 @@ def apply(self, change_request):
         membership_vals = {
             "group": group.id,
             "individual": individual.id,
-            "start_date": fields.Date.today(),
+            "start_date": fields.Datetime.now(),
         }
 
         # Handle relationship/membership type