Ensure we don't import from "graphql.mjs" (#2)

index.js

···
 
               const from = declaration ? declaration.from : PKG_NAME;
               if (!acc[from]) {
-                acc[from] = t.importDeclaration([], t.stringLiteral(from + extension));
+                acc[from] = t.importDeclaration([], t.stringLiteral(from === 'graphql' ? from : from + extension));
               }
 
               const localName = specifier.local.name;