The cause is a change in the check output of new Ruby versions
which include the location of the executable; e.g.

  # Ruby 3.3.8
  -:3: warning: statement not reached
  -:6: syntax error, unexpected end-of-input, expecting `end' or dummy end

  # Ruby 3.4.5
  -:3: warning: statement not reached
  /usr/bin/ruby: -:5: syntax errors found (SyntaxError)

Here’s a patch that updates the regex to account for it. Tests
pass with both Ruby 3.3 and 3.4.