Fix formatting of padding

[mborland]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 98.89%. Comparing base (0113246) to head (1a5b81f).
⚠️ Report is 4 commits behind head on develop.

Files with missing lines	Patch %	Lines
include/boost/int128/format.hpp	95.23%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #306      +/-   ##
===========================================
- Coverage    98.91%   98.89%   -0.02%     
===========================================
  Files           59       59              
  Lines         5243     5262      +19     
  Branches      1609     1614       +5     
===========================================
+ Hits          5186     5204      +18     
- Misses          30       31       +1     
  Partials        27       27              

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