Please ignore this PR until reviewed by @ChrisRackauckas.

Summary

Restore the documentation environment's RuntimeGeneratedFunctions compatibility from 0.6 to 0.5, matching the package's current v0.5.23 version.

Root cause

#136 moved both the package version and docs compatibility to 0.6. #137 then changed the package back to 0.5.23 but left docs/Project.toml requiring 0.6. As a result, the reusable Documentation workflow fails during Pkg.develop(PackageSpec(path=pwd())), before it can build any docs:

empty intersection between RuntimeGeneratedFunctions@0.5.23 and project compatibility 0.6

An actual Pkg-based git bisect from v0.5.22 (18e4b5d) through current master identified #137 (483e2e938e1bfc5b5df6dc3aab0064c7005d08b6) as the first bad commit; #136 (6550973d9290c906b1f61d37d416695e95e63a7c) is the passing control with both versions at 0.6.

This independent clean-master failure was exposed while auditing #138. It is not caused by that serialization change.

Validation

Using Julia 1.12.6, matching CI:

• exact reusable-workflow install command now exits 0: julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
• complete local docs build exits 0: julia --project=docs/ docs/make.jl (doctests, link checks, document checks, and HTML rendering)
• julia --project=. -e 'using Pkg; Pkg.test()'
• Runic 1.7.0: --check --diff .

Clean-master failure evidence:

• https://github.com/SciML/RuntimeGeneratedFunctions.jl/actions/runs/30408235778
• same baseline failure on Restore serialization of dropped runtime-generated functions #138: https://github.com/SciML/RuntimeGeneratedFunctions.jl/actions/runs/30521236734