Remove file which was only running in Ruby < 3.0

Author: eregon

spec/truffleruby.mspec

@@ -61,7 +61,6 @@ class MSpecScript
     spec/ruby/library/syslog
     spec/ruby/library/yaml
     spec/ruby/library/zlib
-    spec/ruby/security/cve_2017_17742_spec.rb
     spec/ruby/security/cve_2019_8321_spec.rb
     spec/ruby/security/cve_2019_8322_spec.rb
     spec/ruby/security/cve_2019_8323_spec.rb