fix: fix posts query paths version

[RiccardoM]

Description

This PR fixes the currently wrong path inside the x/posts gRPC query method.

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• confirmed the correct type prefix in the PR title
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[codecov]

Codecov Report

Merging #978 (16c33a1) into master (987ec5d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #978   +/-   ##
=======================================
  Coverage   80.53%   80.53%           
=======================================
  Files         172      172           
  Lines       15244    15244           
=======================================
  Hits        12277    12277           
  Misses       2440     2440           
  Partials      527      527           

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