fix: Node does not support dir imports for ESM (#118)

Author: alanpoulain

src/index.ts

@@ -3,7 +3,7 @@ export * from "./Field.js";
 export * from "./Operation.js";
 export * from "./Parameter.js";
 export * from "./Resource.js";
-export * from "./graphql";
-export * from "./hydra";
-export * from "./openapi3";
-export * from "./swagger";
+export * from "./graphql/index.js";
+export * from "./hydra/index.js";
+export * from "./openapi3/index.js";
+export * from "./swagger/index.js";