feat: add pre-commit framework

test/t/basicobject.rb

@@ -8,4 +8,3 @@ end
 assert('BasicObject superclass') do
   assert_nil(BasicObject.superclass)
 end
-

test/t/iterations.rb

@@ -58,4 +58,4 @@ assert('next expression', '11.5.2.4.4') do
     end
     all
   end
-end
+end

test/t/object.rb

@@ -8,4 +8,3 @@ end
 assert('Object superclass', '15.2.1.2') do
   assert_equal BasicObject, Object.superclass
 end
-