use explainaboard.serialization.legacy in SDK 0.11.2

[qjiang002]

After updating SDK to version 0.11.2, the web cannot run locally due to import error

[0]   File "/Users/jiangqi/Desktop/Capstone/explainaboard_web/backend/src/gen/explainaboard_web/impl/db_utils/system_db_utils.py", line 17, in <module>
[0]     from explainaboard.utils.serialization import general_to_dict
[0] ModuleNotFoundError: No module named 'explainaboard.utils.serialization'
[0] npm run start-backend exited with code 1

In the new SDK, the general_to_dict function is in explainaboard.serialization.legacy.
Fix import error by using from explainaboard.serialization.legacy import general_to_dict

[lyuyangh]

Thanks! Not sure if @OscarWang114 has started this, but I think we can maybe create a PR that bumps the SDK version and fixes all the breaking changes like this one?

[pfliu-nlp]

Also, here are:

• a discussion about usability tests when performing a version upgrade: Bump version to 0.11.2 ExplainaBoard#492
• a checklist: https://github.com/neulab/explainaboard_web/wiki/Pre-release-Checklist
  I think we at least need to make sure the items in the checklist go smoothly.

[pfliu-nlp]

it looks good to me.

[qjiang002]

Thanks for the checklist. I find another error when submitting the system in this issue #336. This error doesn't relate to the import error in this PR. I'll go ahead to merge this one first.

[lyuyangh]

@qjiang002 Just to clarify, are we running on 0.11.2 already? I think this repo is still using 0.11.1. If we merge this now, it would break our staging and production environment.

[qjiang002]

Thanks @lyuyangh for the reminder. The current requirements still uses 0.11.1. I will not merge this PR now and will put this change in another PR for fixing the bumping version issues together.

[OscarWang114]

Thanks @qjiang002 and @lyuyangh ! I haven't started, and yes feel free to submit another PR

[neubig]

In the future we should convert to the new serialization code, but I think this works for now.

[neubig]

@qjiang002 : does the "invalid" tag mean that this will never be merged? If so I think you can close the PR.