Remove unnecessary Unique validation RuboCop TODO

They probably got unnecessary due to the update of RuboCop, though I
haven't looked into their changelog to confirm.

app/models/notion.rb

@@ -2,7 +2,7 @@ class Notion < ApplicationRecord
   belongs_to :tag, optional: true, touch: true
   belongs_to :aliased_tag, class_name: "Tag", optional: true, touch: true
 
-  validates :title, uniqueness: { scope: :locale } # rubocop:todo Rails/UniqueValidationWithoutIndex
+  validates :title, uniqueness: { scope: :locale }
   validates :title, presence: true
   validate :presence_of_tag, if: :persisted?
 

app/models/term.rb

@@ -4,7 +4,7 @@ class Term < ApplicationRecord
   has_many :lectures
 
   # season can only be SS/WS, and there can be only one of this type each year
-  validates :season, presence: true, # rubocop:todo Rails/UniqueValidationWithoutIndex
+  validates :season, presence: true,
                      inclusion: { in: ["SS", "WS"] },
                      uniqueness: { scope: :year }
   # a year >=2000 needs to be present