Remove stale TODO

Author: david-perez

codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/UnconstrainedMapGenerator.kt

@@ -139,7 +139,6 @@ class UnconstrainedMapGenerator(
                                 withBlock("Some(v) =>", ",") {
                                     // DRYing this up with the else branch below would make this less understandable.
                                     rustTemplate(
-                                        // TODO
                                         """
                                         match #{ConstrainedValueSymbol}::try_from(v)$boxErr {
                                             Ok(v) => Ok((k, Some(v))),