chore: fixes mutability of the Repeat output

[staheri14]

Overview

Closes #2139

Checklist

• New and updated code has appropriate documentation
• New and updated code has new and/or updated testing
• Required CI checks are passing
• Visual proof for any user facing features like CLI or documentation updates
• Linked issues closed with keywords

[codecov-commenter]

Codecov Report

Merging #2140 (0da10b6) into main (b77ac63) will increase coverage by 0.00%.
The diff coverage is 63.63%.

@@           Coverage Diff           @@
##             main    #2140   +/-   ##
=======================================
  Coverage   24.28%   24.28%           
=======================================
  Files         125      125           
  Lines       14248    14260   +12     
=======================================
+ Hits         3460     3463    +3     
- Misses      10432    10440    +8     
- Partials      356      357    +1     

Impacted Files	Coverage Δ
x/blob/types/payforblob.go	69.54% <0.00%> (-4.02%)	⬇️
x/mint/types/constants.go	100.00% <ø> (ø)
pkg/namespace/namespace.go	60.00% <100.00%> (+10.48%)	⬆️
test/txsim/blob.go	80.00% <100.00%> (-0.65%)	⬇️
x/blob/ante/ante.go	85.00% <100.00%> (-3.47%)	⬇️
x/blob/keeper/keeper.go	80.00% <100.00%> (-2.76%)	⬇️

... and 1 file with indirect coverage changes