test: changed timezone for tests

[Pugma]

fix #4416

https://vitest.dev/config/#env を見て、それに合うように vite.config.ts に追記しました

[github-actions]

Preview (prod) → https://4508-prod.traq-preview.trapti.tech/
Preview (dev) → https://4508-dev.traq-preview.trapti.tech/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 8.83%. Comparing base (bf870c9) to head (b546360).
Report is 2 commits behind head on master.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #4508   +/-   ##
======================================
  Coverage    8.83%   8.83%           
======================================
  Files         671     671           
  Lines       29444   29444           
  Branches      524     524           
======================================
  Hits         2601    2601           
  Misses      26837   26837           
  Partials        6       6           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.