[BUG] Weave.jl breaks when using v1.5-rc2

[ChrisRackauckas]

Upstream issue of SciML/SciMLTutorials.jl#294 . @KristofferC says that the recommended fix is to not eval into the module.

[ChrisRackauckas]

ERROR: LoadError: InitError: Evaluation into the closed module `Markdown` breaks incremental compilation because the side effects will not be permanent. This is likely due to some other module mutating `Markdown` with `eval` during precompilation - don't do this.
Stacktrace:
 [1] eval at ./boot.jl:331 [inlined]
 [2] eval at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Markdown/src/Markdown.jl:6 [inlined]
 [3] __init__() at /home/miguel/.julia/packages/Weave/AL87K/src/WeaveMarkdown/markdown.jl:10
 [4] _include_from_serialized(::String, ::Array{Any,1}) at ./loading.jl:697
 [5] _require_search_from_serialized(::Base.PkgId, ::String) at ./loading.jl:782
 [6] _require(::Base.PkgId) at ./loading.jl:1007
 [7] require(::Base.PkgId) at ./loading.jl:928
 [8] require(::Module, ::Symbol) at ./loading.jl:923
 [9] include(::Function, ::Module, ::String) at ./Base.jl:380
 [10] include(::Module, ::String) at ./Base.jl:368
 [11] top-level scope at none:2
 [12] eval at ./boot.jl:331 [inlined]
 [13] eval(::Expr) at ./client.jl:467
 [14] top-level scope at ./none:3
during initialization of module WeaveMarkdown

[aviatesk]

yeah will look into that when I have time.
#357 will "fix" the problem but I would like to see if there is another way to solve this.