[tests] Add EOL to patest_mono.c

Build was failing on Mac because of the missing end-of-line.

test/patest_mono.c

@@ -152,4 +152,5 @@ error:
     fprintf( stderr, "Error number: %d\n", err );
     fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
     return err;
-}
+}
+