fix(BUX-497): update to go-paymail 12.1

[chris-4chain]

Pull Request Checklist

• 📖 I created my PR using provided : CODE_STANDARDS
• 📖 I have read the short Code of Conduct: CODE_OF_CONDUCT
• 🏠 I tested my changes locally.
• ✅ I have provided tests for my changes.
• 📝 I have used conventional commits.
• 📗 I have updated any related documentation.
• 💾 PR was issued based on the Github or Jira issue.

[mergify]

Welcome to our open-source project @chris-4chain! 💘

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c108973) 53.28% compared to head (ac741b5) 53.28%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #546   +/-   ##
=======================================
  Coverage   53.28%   53.28%           
=======================================
  Files         110      110           
  Lines       10854    10854           
=======================================
  Hits         5784     5784           
  Misses       4605     4605           
  Partials      465      465           

Flag	Coverage Δ
unittests	53.28% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c108973...ac741b5. Read the comment docs.