Fix incorrect regex pattern in time_duration_is_valid function

[prjanitor]

Summary

Fixed a malformed regex pattern in the time_duration_is_valid function that prevented valid time duration strings from being accepted.

Changes

• Updated the regex pattern from ^((((\d{1,2}:)?[0-5])?\d:)?[0-5])?\d$ to ^\d{1,2}:\d{2}:\d{2}$
• The new pattern correctly validates HH:MM:SS format with:
  • 1-2 digits for hours
  • Exactly 2 digits for minutes
  • Exactly 2 digits for seconds

Testing

Valid formats now accepted:

• 1:23:45
• 12:34:56
• 0:00:00

Invalid formats correctly rejected:

• 1:2:3 (single digit minutes/seconds)
• 123:45:67 (too many digits)
• 12:34 (missing seconds)

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