remove get_matching_type overload

[penelopeysm]

Terrifyingly, Turing overloaded an internal DynamicPPL function, get_matching_type. The function was renamed in a patch release, which is semver compliant. However, that makes Turing error when loaded, because there is no longer such a function to overload. This PR removes the overload (it was dead code and not accomplishing anything anyway).

[github-actions]

Turing.jl documentation for PR #2748 is available at:
https://TuringLang.github.io/Turing.jl/previews/PR2748/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.65%. Comparing base (969f39a) to head (b35bf9c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2748      +/-   ##
==========================================
+ Coverage   86.51%   86.65%   +0.13%     
==========================================
  Files          20       20              
  Lines        1261     1259       -2     
==========================================
  Hits         1091     1091              
+ Misses        170      168       -2     

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[mhauru]

Gee, thanks for catching this quickly, that was nasty.