Fix tx REST encoding

[aaronc]

Description

closes: #XXXX

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Before we can merge this PR, please make sure that all the following items have been
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write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

[codecov]

Codecov Report

Merging #6467 into master will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master    #6467   +/-   ##
=======================================
  Coverage   56.06%   56.06%           
=======================================
  Files         466      466           
  Lines       27904    27904           
=======================================
  Hits        15643    15643           
  Misses      11149    11149           
  Partials     1112     1112