Update check for Ractor experimental warning

Fix: #270

Author: byroot

test/support/raise_warnings.rb

@@ -3,7 +3,7 @@
 $VERBOSE = true
 module RaiseWarnings
   def warn(message, *)
-    return if message.include?('Ractor is experimental')
+    return if message.match?(/Ractor.*is experimental/)
 
     super