style: add trailing newline to types/index.tst.ts

Author: Puppo

types/index.tst.ts

@@ -141,4 +141,4 @@ expect(writer).type.toBe<SerializerFactory>()
   const compiler = factory(schemaMap)
   expect(compiler).type.toBe<SerializerCompiler>()
   expect(compiler(endpointSchema)).type.toBe<Serializer>()
-}
+}