Tests for version 0.21.8 are failing in ruby 3.2.2 with rbs 2.8.2

[Segaja]

When running the tests for this gem I get the following error:

(none):1: warning: possibly useless use of a literal in void context
Loaded suite /usr/lib/ruby/gems/3.2.0/gems/rake-13.0.6/lib/rake/rake_test_loader
Started
....Initialized empty Git repository in /build/ruby-typeprof/src/typeprof-0.21.8/testbed/diff-lcs/.git/
From https://github.com/mame/diff-lcs
 * branch            de838d2df80514adbf22c26daed728ddd06af60b -> FETCH_HEAD
.(none):25: warning: possibly useless use of a constant in void context
path/to/file:25: warning: possibly useless use of a constant in void context
....TypeProf for IDE is started successfully
......................................................................
...............................................................................
............F
===============================================================================
Failure: test: smoke/integer.rb(TypeProf::SmokeTest)
/build/ruby-typeprof/src/typeprof-0.21.8/test/typeprof/smoke_test.rb:36:in `block (2 levels) in <class:SmokeTest>'
     33:           expected = actual
     34:         end
     35:
  => 36:         assert_equal(expected, actual)
     37:       end
     38:     end
     39:   end
<"# Classes\n" +
"class Object\n" +
"  private\n" +
"  def foo: (Integer? x) -> nil\n" +
"end\n"> expected but was
<"# Classes\n" +
"class Object\n" +
"  private\n" +
"  def foo: (Integer x) -> nil\n" +
"end\n">

diff:
  # Classes
  class Object
    private
?   def foo: (Integer? x) -> nil
  end
===============================================================================
...............................................................................
....................................................................
Finished in 43.381750919 seconds.
-------------------------------------------------------------------------------
318 tests, 361 assertions, 1 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications
99.6855% passed
-------------------------------------------------------------------------------
7.33 tests/s, 8.32 assertions/s
rake aborted!
Command failed with status (1)

Tasks: TOP => test
(See full trace by running task with --trace)

This seems to be a regression from 30a334e which is designed to make the tests compatible to rbs 3.2.0. This seems to make the tests only support rbs >= 3.2.0, but the gemspec file stills says rbs >= 1.8.1 is required and supported: https://github.com/ruby/typeprof/blob/v0.21.8/typeprof.gemspec#L33

So I guess either the test needs to be updated to somehow support all the rbs versions, or the gem needs to update its requirements for the minimal required version of rbs.