Hi and welcome.
IIUC the problem comes from the fact that AbstractPPL starting with v0.5.3 tightened their compat bounds to (https://github.com/TuringLang/AbstractPPL.jl/blob/0f289206b22da5feee03218c157afb28706ed8ec/Project.toml#L19)
julia = "~1.6.6, 1.7.3"
But in the repo of the PR you linked the CI is configured to run on Julia v1.7.2, cf. https://github.com/xKDR/CRRao.jl/blob/compathelper/new_version/2023-06-16-00-53-51-932-00744874042/.github/workflows/ci.yml. Hence you see this line
└─restricted by julia compatibility requirements to versions: 0.1.0-0.5.2 or uninstalled
So perhaps try bumping the Julia version in CI.