fix: make field '_id' optional in filter argument

In some cases, some resolver were making the filter._id argument required.

This is a minor change that doesn't break any code.
since that all the arguments in Filter are optional unless makeRequired is defined in options

Author: israelglar

src/resolvers/helpers/filter.js

@@ -69,6 +69,8 @@ export const filterHelperArgs = (
   const filterTypeName: string = opts.filterTypeName;
   const itc = typeComposer.getInputTypeComposer().clone(filterTypeName);
 
+  itc.makeOptional('_id');
+
   itc.addFields({
     _ids: [GraphQLMongoID],
   });