Fixes read the docs

[mcbarton]

Description

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@vgvassilev This PR will fix the read the docs giving us the developer documentation again. The other day I was fixing the deployment blind as I didn't know about the build logs. Here it is for the most recent build https://readthedocs.org/projects/cppinterop/builds/26507232/ . By expanding the python -m sphinx -T -b html -d _build/doctrees -D language=en . $READTHEDOCS_OUTPUT/html command you see we fail due to the following error

CMake Error at CMakeLists.txt:238 (message):
  We need either USE_CLING or USE_REPL

This PR will fix that by defining that we want to use the repl when building the docs. The build logs explain why we still get some of the documentation, see

writing output... [ 14%] DevelopersDocumentation
writing output... [ 29%] FAQ
writing output... [ 43%] InstallationAndUsage
writing output... [ 57%] UsingCppInterOp
writing output... [ 71%] index
writing output... [ 86%] reference
writing output... [100%] tutorials

Fixes # (issue)

Type of change

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• Bug fix
• New feature
• Requires documentation updates

Testing

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Checklist

• I have read the contribution guide recently

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.15%. Comparing base (1c3f884) to head (ab20320).
Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   76.15%   76.15%           
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  Files           8        8           
  Lines        3137     3137           
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  Hits         2389     2389           
  Misses        748      748