Loosen bounds on merkle hash arguments

[preston-evans98]

Closes #1310

• Referenced an issue explaining the need for the change
• Updated all relevant documentation in docs
• Updated all code comments where relevant
• [] Wrote tests (N/A)
• Added entry in .changelog/

[codecov-commenter]

Codecov Report

Merging #1311 (8f7b091) into main (2238d4b) will increase coverage by 0.0%.
The diff coverage is 100.0%.

❗ Current head 8f7b091 differs from pull request most recent head a888163. Consider uploading reports for the commit a888163 to get more accurate results

@@          Coverage Diff          @@
##            main   #1311   +/-   ##
=====================================
  Coverage   60.3%   60.3%           
=====================================
  Files        275     275           
  Lines      24420   24420           
=====================================
+ Hits       14738   14739    +1     
+ Misses      9682    9681    -1     

Impacted Files	Coverage Δ
tendermint/src/merkle.rs	96.7% <100.0%> (ø)

... and 3 files with indirect coverage changes

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