Add dyn-upcasting-coercion-initiative under automation

[Kobzol]

Repo: https://github.com/rust-lang/dyn-upcasting-coercion-initiative

Extracted from GH:

org = "rust-lang"
name = "dyn-upcasting-coercion-initiative"
description = "Initiative to support upcasting dyn Trait values to supertraits"
bots = []

[access.teams]
lang = "maintain"
security = "pull"
initiative-dyn-upcasting = "write"

[access.individuals]
rust-lang-owner = "admin"
nikomatsakis = "maintain"
scottmcm = "maintain"
pnkfelix = "maintain"
jdno = "admin"
rylev = "admin"
tmandry = "maintain"
badboy = "admin"
crlf0710 = "write"
pietroalbini = "admin"
Mark-Simulacrum = "admin"
joshtriplett = "maintain"

[compiler-errors]

dyn upcasting is not stable

[Kobzol]

Ah, I didn't notice rust-lang/rust#120233. The initiative repository (and project group?) doesn't seem active though.

[ehuss]

I think as long as there is a project-dyn-upcasting group, it is fine to add the repo owned by them. They may not be visibly active, but I think it would be good to keep it live until the project is actually finished. According to rust-lang/rust#120222, there are people actively working on it.

[Kobzol]

Ok, modified it so that it is under under team, but not archived.