Fix specs not to use should syntax

spec/rspec/support/comparable_version_spec.rb

@@ -31,7 +31,7 @@ module RSpec::Support
             ComparableVersion.new(subject_string) <=> ComparableVersion.new(other_string)
           end
 
-          it { should eq(expected) }
+          it { is_expected.to eq(expected) }
         end
       end
     end

spec/rspec/support_spec.rb

@@ -123,23 +123,23 @@ def method_missing(name, *args, &block)
           'foo'
         end
 
-        it { should equal(String) }
+        it { is_expected.to equal(String) }
       end
 
       context 'with a BasicObject instance' do
         let(:object) do
           BasicObject.new
         end
 
-        it { should equal(BasicObject) }
+        it { is_expected.to equal(BasicObject) }
       end
 
       context 'with nil' do
         let(:object) do
           nil
         end
 
-        it { should equal(NilClass) }
+        it { is_expected.to equal(NilClass) }
       end
 
       context 'with an object having a singleton class' do
@@ -162,7 +162,7 @@ def object.some_method
           String
         end
 
-        it { should equal(Class) }
+        it { is_expected.to equal(Class) }
       end
     end