Use a default for DeprecationStrategy

This makes it so we can change it in one place in the future.

Author: LegNeato

graphql_client_codegen/src/deprecation.rs

@@ -17,6 +17,10 @@ pub enum DeprecationStrategy {
     Warn,
 }
 
+impl Default for DeprecationStrategy {
+    fn default() -> Self { DeprecationStrategy::Warn }
+}
+
 pub fn extract_deprecation_strategy(
     ast: &syn::DeriveInput,
 ) -> Result<DeprecationStrategy, failure::Error> {

graphql_query_derive/src/lib.rs

@@ -34,7 +34,7 @@ fn build_graphql_client_derive_options(input: &syn::DeriveInput) -> GraphQLClien
     let response_derives = attributes::extract_attr(input, "response_derives").ok();
     // The user can determine what to do about deprecations.
     let deprecation_strategy = deprecation::extract_deprecation_strategy(input)
-        .unwrap_or(deprecation::DeprecationStrategy::Warn);
+        .unwrap_or(deprecation::DeprecationStrategy::default());
 
     GraphQLClientDeriveOptions {
         selected_operation: input.ident.to_string(),