Exclude failing test_syntax.rb due to different messages in Prism

Author: eregon

test/mri/excludes/TestSyntax.rb

@@ -61,3 +61,12 @@
 exclude :test_anonymous_keyword_rest_forwarding, "/home/eregon/code/truffleruby-ws/truffleruby/test/mri/tests/ruby/test_syntax.rb:158:in `test_anonymous_keyword_rest_forwarding'."
 exclude :test_script_lines_encoding, "pid 42586 exit 0."
 exclude :test_class_module_Object_ancestors, "TypeError: 1:Integer is not a class"
+exclude :test_unassignable, "prism"
+exclude :test_anonymous_block_forwarding, "prism"
+exclude :test_newline_in_block_parameters, "prism"
+exclude :test_invalid_symbol_space, "prism"
+exclude :test_keywords_specified_and_not_accepted, "prism"
+exclude :test_unexpected_fraction, "prism"
+exclude :test_heredoc_cr, "prism"
+exclude :test_no_label_with_percent, "prism"
+exclude :test_keyword_duplicated, "prism"