spec: Fix compatibility with Ruby 3.4.0 in ranges (#191)

[CI in the
upstream](https://github.com/mrkn/pycall.rb/actions/runs/12501779028/job/34879787889)
fails for the latest Ruby version 3.4:
```
  1) PyCall::PyObjectWrapper#[] when the given index is an Enumerable that is created by Range#step is expected to eq [2, 4, 6, 8]
     Failure/Error: expect(list[(nil..nil).step(-1)]).to eq(PyCall::List.new([*1..10].reverse))

     ArgumentError:
       #step for non-numeric beginless ranges is meaningless
     # ./spec/pycall/pyobject_wrapper_spec.rb:164:in 'Range#step'
     # ./spec/pycall/pyobject_wrapper_spec.rb:164:in 'block (4 levels) in <module:PyCall>'
```
It looks like this happens due [to this change in the most recent Ruby
version](https://github.com/ruby/ruby/blame/master/range.c#L524-L527)
which doesn't allow to use "beginless" ranges anymore.

This PR sets the range explicitly so we can avoid failing with an
exception

See also:
* https://bugs.ruby-lang.org/issues/18368
* ruby/ruby#7444

---------

Co-authored-by: Kenta Murata <[email protected]>
Co-authored-by: Sutou Kouhei <[email protected]>
Co-authored-by: kojix2 <[email protected]>

Author: 4 people

spec/pycall/pyobject_wrapper_spec.rb

@@ -161,8 +161,11 @@ module PyCall
           list = PyCall::List.new([*1..10])
           expect(list[(1..-1).step(2)]).to eq(PyCall::List.new([2, 4, 6, 8, 10]))
           expect(list[(1..-2).step(2)]).to eq(PyCall::List.new([2, 4, 6, 8]))
-          expect(list[(nil..nil).step(-1)]).to eq(PyCall::List.new([*1..10].reverse))
           expect(list[(-1..0).step(-1)]).to eq(PyCall::List.new([*1..10].reverse))
+          # In Ruby 3.4+, step for non-numeric beginless ranges raises ArgumentError
+          if Gem::Version.new(RUBY_VERSION) < Gem::Version.new('3.4.0')
+            expect(list[(nil..nil).step(-1)]).to eq(PyCall::List.new([*1..10].reverse))
+          end
           expect(list[(-1...0).step(-1)]).to eq(PyCall::List.new([*2..10].reverse))
           expect(list[(-2..2).step(-2)]).to eq(PyCall::List.new([9, 7, 5, 3]))
           expect(list[(-2...2).step(-2)]).to eq(PyCall::List.new([9, 7, 5]))