Update Meta in builder 07 test

Current (`^2.0.0`) version of `Attribute` doc explains `Meta` pretty
well

Author: skaunov

builder/tests/07-repeated-field.rs

@@ -26,8 +26,7 @@
 // Resources:
 //
 //   - Relevant syntax tree types:
-//     https://docs.rs/syn/1.0/syn/struct.Attribute.html
-//     https://docs.rs/syn/1.0/syn/enum.Meta.html
+//     https://docs.rs/syn/2.0/syn/struct.Attribute.html
 
 use derive_builder::Builder;