Issue building with Julia 1.12

```julia> using Franklin julia> serve() ERROR: UndefVarError: `generate_rss` not defined in `Main.MD_DEFINITIONS` The binding may be too new: running in world age 38670, while current world is 38695. Stacktrace: [1] getproperty @ ./Base_compiler.jl:47 [inlined] [2] process_mddefs(blocks::Vector{Franklin.OCBlock}, isconfig::Bool, pagevar::Bool, isinternal::Bool) @ Franklin ~/.julia/packages/Franklin/X68Y3/src/converter/markdown/mddefs.jl:36 [3] convert_md(mds::String, pre_lxdefs::Vector{…}; isrecursive::Bool, isinternal::Bool, isconfig::Bool, has_mddefs::Bool, pagevar::Bool, nostripp::Bool) @ Franklin ~/.julia/packages/Franklin/X68Y3/src/converter/markdown/md.jl:129 [4] convert_md (repeats 2 times) @ ~/.julia/packages/Franklin/X68Y3/src/converter/markdown/md.jl:23 [inlined] [5] process_config() @ Franklin ~/.julia/packages/Franklin/X68Y3/src/manager/file_utils.jl:15 [6] @ Franklin ~/.julia/packages/Franklin/X68Y3/src/manager/franklin.jl:98 [7] serve() @ Franklin ~/.julia/packages/Franklin/X68Y3/src/manager/franklin.jl:49 [8] top-level scope @ REPL[2]:1 Some type information was truncated. Use `show(err)` to see complete types. ```