fix: Changes are no longer detected when start and end time are left empty in tmpo edit

[DylanDevelops]

Pull Request Checklist

• I have read and followed the contribution guidelines.
• My pull request targets the main branch of tmpo.
• I have tested these changes locally on my machine.

Closes #31

Description

This pull request improves the accuracy of change detection in the entry editing command by ensuring time comparisons only consider minute-level precision. This prevents false positives when comparing timestamps that may have different second or sub-second values but are otherwise equivalent at the minute level.

Key changes:

Time comparison precision:

• Updated the comparison logic in the EditCmd command to truncate both the original and edited start and end times to the nearest minute before checking for changes, ensuring only meaningful differences are detected.

Dependency update:

• Added the time package import in cmd/entries/edit.go to support time truncation operations.