Ignore stubs file by rubocop

Author: pitr-ch

.rubocop.yml

@@ -8,6 +8,7 @@ AllCops:
     - 'lib/truffle/date/delta/parser.rb' # generated code
     - 'lib/truffle/socket/mri.rb' # taken from MRI
     - 'lib/truffle/ffi/**/*.rb' # taken from FFI gem
+    - 'lib/truffle/truffle/stubs.rb' # has embeded Java which confuses Rubocop
     - 'src/test/ruby/types.rb' # deliberately strange code for debugging purposes
     - 'src/tck/ruby/lexical-context.rb' # deliberately strange code for debugging purposes
 
@@ -373,4 +374,4 @@ Style/StringLiterals:
 # Supports --auto-correct
 Style/UnlessElse:
   Description: Checks for unless expressions with else clauses.
-  Enabled: true
+  Enabled: true