Tests fail on upcoming 1.12 (`BigFloat cannot be finalized because they are not mutable`)

[KristofferC]

objects of type BigFloat cannot be finalized because they are not mutable
  Stacktrace:
    [1] error(::String, ::Type, ::String)
      @ Base ./error.jl:54
    [2] _check_mutable(o::Any)
      @ Base ./gcutils.jl:41
    [3] finalizer(f::Any, o::Any)
      @ Base ./gcutils.jl:85
    [4] intern!
      @ ~/.julia/packages/InternedStrings/JTzem/src/InternedStrings.jl:39 [inlined]
    [5] intern(::Type{BigFloat}, s::BigFloat)
      @ InternedStrings ~/.julia/packages/InternedStrings/JTzem/src/InternedStrings.jl:78
    [6] intern(s::BigFloat)
      @ InternedStrings ~/.julia/packages/InternedStrings/JTzem/src/InternedStrings.jl:66
    [7] top-level scope
      @ ~/.julia/packages/InternedStrings/JTzem/test/all_kinds_of_types.jl:49
    [8] macro expansion
      @ /opt/julia/share/julia/stdlib/v1.12/Test/src/Test.jl:1771 [inlined]
    [9] macro expansion
      @ ~/.julia/packages/InternedStrings/JTzem/test/all_kinds_of_types.jl:50 [inlined]
   [10] include(mapexpr::Function, mod::Module, _path::String)
      @ Base ./Base.jl:308

[oxinabox]

Nice improvement to the language