Increase time range for authentication spec (#932)

In commit ce17d2d some specs were added
to verify that the time it takes to authenticate users that already
exist and those that don't is within 0.001s. This causes the tests to
fail randomly given that the time range is too precise. We are
increasing this range to 0.01 to avoid flaky tests.

spec/models/user_spec.rb

@@ -59,7 +59,7 @@
         User.authenticate("[email protected]", password)
       end
 
-      expect(user_does_not_exist_time). to be_within(0.001).of(user_exists_time)
+      expect(user_does_not_exist_time). to be_within(0.01).of(user_exists_time)
     end
 
     it "takes the same amount of time to fail authentication regardless of whether user exists" do
@@ -73,7 +73,7 @@
         User.authenticate("[email protected]", "bad_password")
       end
 
-      expect(user_does_not_exist_time). to be_within(0.001).of(user_exists_time)
+      expect(user_does_not_exist_time). to be_within(0.01).of(user_exists_time)
     end
 
     it "is retrieved via a case-insensitive search" do