Remove Formatting.jl from dependencies

[phlaster]

Just copy+pasting the warning message I got at the precompilation of Plots.jl:

Formatting.jl has been unmaintained for a while, with some serious
correctness bugs compromising the original purpose of the package. As a result,
it has been deprecated - consider using an alternative, such as
`Format.jl` (https://github.com/JuliaString/Format.jl) or the `Printf` stdlib directly.

If you are not using Formatting.jl as a direct dependency, please consider
opening an issue on any packages you are using that do use it as a dependency.
From Julia 1.9 onwards, you can query `]why Formatting` to figure out which
package originally brings it in as a dependency.

[hyrodium]

This issue will be fixed by #281.

[korsbo]

This should be fixed by #281 now