ruby-head: Set’s inspect has changed to "<_MySet: {1, 2}>", which fails one test in the suite

[olleolleolle]

The inspect display has changed and that tripped up tests in current ruby-head:

<"_MySet[1, 2]"> expected but was
<"#<_MySet: {1, 2}>”>

How tests fail

Failure: test_inspect(TC_Set)
/home/runner/work/set/set/test/test_set.rb:801:in 'TC_Set#test_inspect'
     798: 
     799:       c = Class.new(Set)
     800:       c.set_temporary_name("_MySet")
  => 801:       assert_equal('_MySet[1, 2]', c[1, 2].inspect)
     802:     end
     803: 
     804:     def test_to_s
<"_MySet[1, 2]"> expected but was
<"#<_MySet: {1, 2}>">

diff:
?   _MySet[  1, 2] 
? #<      : {    }>
? ++      ?    ?
Error: <"_MySet[1, 2]"> expected but was
<"#<_MySet: {1, 2}>">.
===============================================================================

[jeremyevans]

@knu I think we should drop ruby-head testing from this repository. Set is a core class in Ruby 4+ and this library is a no-op in Ruby 4+. I notice the guard at the top of set.rb needs to be updated, I'll submit a PR for both issues.