PUBLIC: Add missing extra-traits feature flag for syn dependency.

This fixes gtest_rust not compiling with Cargo and therefore unblocks the release.

PiperOrigin-RevId: 734609762

Author: Googler

googletest_macro/Cargo.toml

@@ -27,7 +27,7 @@ authors = [
 
 [dependencies]
 quote = "1.0.39"
-syn = {version = "2.0.99", features = ["full"]}
+syn = {version = "2.0.99", features = ["full", "extra-traits"]}
 proc-macro2 = "1.0.94"
 
 [lib]