Fixed Ruby 3.1 tests by marking intersect? as unimplemented. (#9645)

* Fixed Ruby 3.1 tests by marking intersect? as unimplemented.

* Updated compatibility tests.

ruby/compatibility_tests/v3.0.0/tests/repeated_field_test.rb

@@ -21,6 +21,7 @@ class RepeatedFieldTest < Test::Unit::TestCase
       :nitems, :iter_for_reverse_each, :indexes, :append, :prepend]
     arr_methods -= [:union, :difference, :filter!]
     arr_methods -= [:intersection, :deconstruct] # ruby 2.7 methods we can ignore
+    arr_methods -= [:intersect?] # ruby 3.1 methods we can ignore
     arr_methods.each do |method_name|
       assert m.repeated_string.respond_to?(method_name) == true, "does not respond to #{method_name}"
     end

ruby/tests/repeated_field_test.rb

@@ -21,6 +21,7 @@ class RepeatedFieldTest < Test::Unit::TestCase
       :nitems, :iter_for_reverse_each, :indexes, :append, :prepend]
     arr_methods -= [:union, :difference, :filter!]
     arr_methods -= [:intersection, :deconstruct] # ruby 2.7 methods we can ignore
+    arr_methods -= [:intersect?] # ruby 3.1 methods we can ignore
     arr_methods.each do |method_name|
       assert m.repeated_string.respond_to?(method_name) == true, "does not respond to #{method_name}"
     end