Fix more tests

Author: mcmire

spec/support/unit/matchers/be_deprecated_in_favor_of.rb

@@ -14,7 +14,7 @@ def matches?(old_constant_name)
         @old_constant_name = old_constant_name
         @actual_output =
           SuperDiff::UnitTests.capture_warnings do
-            old_constant_name.constantize
+            Object.const_get(old_constant_name)
           end
         @actual_output.start_with?(expected_prefix)
       end

spec/unit/deprecations_spec.rb

@@ -91,8 +91,8 @@
   RSpec.describe old_constant_name, type: :unit do
     it "maps to #{new_constant_name}" do
       capture_warnings do
-        expect(old_constant_name.constantize).to be(
-          new_constant_name.constantize
+        expect(Object.const_get(old_constant_name)).to be(
+          Object.const_get(new_constant_name)
         )
       end
     end