Use dynamic times and dates in factories (part 2)

Most factories were using dynamic times and dates since commit 0cf799a.
However:

* At the time, commits AyuntamientoMadrid/consul@71f5351 and
AyuntamientoMadrid/consul@a476a30 (which introduced static times/dates
in factories) hadn't been backported.
* The changes in commit 0cf799a overlooked the factory
`proposal_notification`.

spec/factories/budgets.rb

@@ -149,11 +149,11 @@ FactoryBot.define do
     end
 
      trait :hidden do
-       hidden_at Time.current
+       hidden_at { Time.current }
      end
 
      trait :with_ignored_flag do
-       ignored_flag_at Time.current
+       ignored_flag_at { Time.current }
      end
 
     trait :flagged do
@@ -163,7 +163,7 @@ FactoryBot.define do
      end
 
      trait :with_confirmed_hide do
-       confirmed_hide_at Time.current
+       confirmed_hide_at { Time.current }
      end
   end
 

spec/factories/notifications.rb

@@ -18,7 +18,7 @@ FactoryBot.define do
 
     trait :sent do
       recipients_count 1
-      sent_at Time.current
+      sent_at { Time.current }
     end
   end
 end

spec/factories/proposals.rb

@@ -64,15 +64,15 @@ FactoryBot.define do
     end
 
     trait :ignored do
-      ignored_at Date.current
+      ignored_at { Date.current }
     end
 
     trait :hidden do
-      hidden_at Date.current
+      hidden_at { Date.current }
     end
 
     trait :with_confirmed_hide do
-      confirmed_hide_at Time.current
+      confirmed_hide_at { Time.current }
     end
   end