fix: timeJoined

[sattvikc]

Summary of change

(A few sentences about this PR)

Related issues

• API not compliant to swagger #377

Test Plan

(Write your test plan here. If you changed any code, please provide us with clear instructions on how you verified your changes work. Bonus points for screenshots and videos!)

Documentation changes

(If relevant, please create a PR in our docs repo, or create a checklist here highlighting the necessary changes)

Checklist for important updates

• Changelog has been updated
• coreDriverInterfaceSupported.json file has been updated (if needed)
  • Along with the associated array in supertokens/constants.go
• frontendDriverInterfaceSupported.json file has been updated (if needed)
• Changes to the version if needed
  • In supertokens/constants.go > version variable
• Had installed and ran the pre-commit hook
• If new thirdparty provider is added,
  • update switch statement in recipe/thirdparty/providers/config_utils.go file, createProvider function.
  • add an icon on the user management dashboard.
• Issue this PR against the latest non released version branch.
  • To know which one it is, run find the latest released tag (git tag) in the format vX.Y.Z, and then find the latest branch (git branch --all) whose X.Y is greater than the latest released tag.
  • If no such branch exists, then create one from the latest released branch.
• If access token structure has changed
  • Modified test in session/accessTokenVersions_test.go to account for any new claims that are optional or omitted by the core

Remaining TODOs for this PR

• Item1
• Item2