Use deepcopy to copy form section info

Previously, copying the form sections was using `list.copy` which
creates a shallow copy of the list. Since the `TASK_ORDER_SECTIONS` list
contains a couple dictionaries, this was just creating another list with
references to the same dictionaries.

Therefore, when a section was marked as completed, it was updated
globally and visiting the new task order without filling anything out
would show some sections as completed.

atst/routes/task_orders/new.py

@@ -1,3 +1,5 @@
+from copy import deepcopy
+
 from flask import (
     request as http_request,
     render_template,
@@ -90,7 +92,7 @@ class ShowTaskOrderWorkflow:
 
     @property
     def display_screens(self):
-        screen_info = TASK_ORDER_SECTIONS.copy()
+        screen_info = deepcopy(TASK_ORDER_SECTIONS)
 
         if self.task_order:
             for section in screen_info: