Add and apply RSpec/BeEq rubocop rule

This rule was added in rubocop-rspec 2.9.0. Once again, we were applying
it about 50% of the time.

spec/shared/models/notifiable.rb

@@ -20,14 +20,14 @@ shared_examples "notifiable" do
     it "returns true when it's a root comment and the notifiable is available" do
       notification = create(:notification, notifiable: notifiable)
 
-      expect(notification.notifiable_available?).to be(true)
+      expect(notification.notifiable_available?).to be true
     end
 
     it "returns true when it's a reply to comment and the notifiable is available" do
       comment = create(:comment, commentable: notifiable)
       notification = create(:notification, notifiable: comment)
 
-      expect(notification.notifiable_available?).to be(true)
+      expect(notification.notifiable_available?).to be true
     end
 
     it "returns false when it's a root comment and the notifiable has been hidden" do
@@ -36,7 +36,7 @@ shared_examples "notifiable" do
       notifiable.hide
       notification.reload
 
-      expect(notification.notifiable_available?).not_to be(true)
+      expect(notification.notifiable_available?).not_to be true
     end
 
     it "returns false when it's a reply to comment and the commentable has been hidden" do
@@ -46,26 +46,26 @@ shared_examples "notifiable" do
       notifiable.hide
       notification.reload
 
-      expect(notification.notifiable_available?).to be(false)
+      expect(notification.notifiable_available?).to be false
     end
   end
 
   describe "check_availability" do
     it "returns true if the resource is present, not hidden, nor retired" do
       notification = create(:notification, notifiable: notifiable)
-      expect(notification.check_availability(notifiable)).to be(true)
+      expect(notification.check_availability(notifiable)).to be true
     end
 
     it "returns false if the resource is not present" do
       notification = create(:notification, notifiable: notifiable)
       notifiable.really_destroy!
-      expect(notification.check_availability(notifiable)).to be(false)
+      expect(notification.check_availability(notifiable)).to be false
     end
 
     it "returns false if the resource is not hidden" do
       notification = create(:notification, notifiable: notifiable)
       notifiable.hide
-      expect(notification.check_availability(notifiable)).to be(false)
+      expect(notification.check_availability(notifiable)).to be false
     end
 
     it "returns false if the resource is retired" do
@@ -74,7 +74,7 @@ shared_examples "notifiable" do
       if notifiable.respond_to?(:retired_at)
         notifiable.update!(retired_at: Time.current, retired_reason: "unfeasible",
                            retired_explanation: "Unfeasibility explanation ...")
-        expect(notification.check_availability(notifiable)).to be(false)
+        expect(notification.check_availability(notifiable)).to be false
       end
     end
   end