Add support for trainings.list endpoint (#51)

Author: mattt

index.d.ts

@@ -130,6 +130,7 @@ declare module 'replicate' {
       ): Promise<Training>;
       get(training_id: string): Promise<Training>;
       cancel(training_id: string): Promise<Training>;
+      list(): Promise<Page<Training>>;
     };
   }
 }

index.js

@@ -61,6 +61,7 @@ class Replicate {
       create: trainings.create.bind(this),
       get: trainings.get.bind(this),
       cancel: trainings.cancel.bind(this),
+      list: trainings.list.bind(this),
     };
   }