Fix #184, fix modal with deleting timetable

[callasio]

Resolve Issue #184

스크린샷

삭제 확인 모달	삭제 불가 모달

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 17 lines in your changes missing coverage. Please review.

Project coverage is 31.10%. Comparing base (575f342) to head (d0cb5ef).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/pages/timetable_page.dart	0.00%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #193      +/-   ##
==========================================
- Coverage   31.13%   31.10%   -0.03%     
==========================================
  Files          80       80              
  Lines        4847     4851       +4     
==========================================
  Hits         1509     1509              
- Misses       3338     3342       +4     

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[sboh1214]

@callasio

아래 링크 참조하시면 됩니다.

https://stackoverflow.com/questions/69568862/flutter-showdialog-is-not-shown-on-popupmenuitem-tap

WidgetsBinding.instance.addPostFrameCallback((_) {});