Upgrade package syncfusion_flutter_calendar from 27.2.5 to 28.2.3

[palisadoes]

Rationale

1. This was previously attempted by the automated dependabot job but the PR tests failed.
2. This issue has been created to fix the issue as there may be multiple dependency requirements that need updating

If this is a major revision upgrade, then many files may need to be updated to the new syntax, in their functions, methods and classes

Background Failing PRs

• Bump syncfusion_flutter_calendar and syncfusion_flutter_datepicker #2725
• https://github.com/PalisadoesFoundation/talawa/actions/runs/13084978705/job/36515002471?pr=2725

[may-tas]

Let me resolve this.
Thanks.

[MayankJha014]

@palisadoes Sir can you assign this to me