∞-∞ should not be ambiguous

[dlfivefifty]

julia> ∞-∞
ERROR: MethodError: -(::InfiniteArrays.Infinity, ::InfiniteArrays.Infinity) is ambiguous. Candidates:
  -(x::Integer, ::InfiniteArrays.Infinity) in InfiniteArrays at /Users/sheehanolver/.julia/packages/InfiniteArrays/YkwcB/src/Infinity.jl:58
  -(x::Number, ::InfiniteArrays.Infinity) in InfiniteArrays at /Users/sheehanolver/.julia/packages/InfiniteArrays/YkwcB/src/Infinity.jl:53
  -(::InfiniteArrays.Infinity, ::Integer) in InfiniteArrays at /Users/sheehanolver/.julia/packages/InfiniteArrays/YkwcB/src/Infinity.jl:57
Possible fix, define
  -(::InfiniteArrays.Infinity, ::InfiniteArrays.Infinity)
Stacktrace:
 [1] top-level scope at none:0

Probably we want a NotANumber type for this. (Note NotANumber() isa Number will return true 🤣)

[dlfivefifty]

This was fixed:

julia> ∞-∞
InfiniteArrays.NotANumber()