chore: update mux.js to v7.0.3

[wseymour15]

Description

update mux.js to v7.0.3

This includes a fix for some unexpected 608 caption behavior.

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
• Reviewed by Two Core Contributors

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.27%. Comparing base (0e9d9d8) to head (3e36978).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1498   +/-   ##
=======================================
  Coverage   86.27%   86.27%           
=======================================
  Files          43       43           
  Lines       10884    10884           
  Branches     2504     2504           
=======================================
  Hits         9390     9390           
  Misses       1494     1494           

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