Switch from attobot to Registrator.jl

[carstenbauer]

See https://discourse.julialang.org/t/switching-package-registration-systems-on-monday/22677/

From today on, Julia doesn't rely on METADATA.jl anymore but instead uses JuliaRegistries/General.

Hence, one has to switch from using attobot to using Registrator.jl.

[carstenbauer]

JuliaLang/Pkg.jl#1133

REQUIRE -> Project.toml script

[carstenbauer]

Let's try triggering Registrator:

@JuliaRegistrator register()

[JuliaRegistrator]

Registration pull request created: JuliaRegistries/General/191

After the above pull request is merged, it is recommended that you create
a tag on this repository for the registered package version:

git tag -a v0.2.1 -m "<description of version>" 9531b3c73aef9e2108099f1eef90d962838c6c3b
git push origin v0.2.1

[carstenbauer]

Nice, that worked. Let's wait until the PR to General.jl is merged and see if TagBot creates a new github tag/release.

[carstenbauer]

Neat, worked as well.