add validation: if trusted publishing is defined, corresponding environment should exist

if a repo toml file contains:
```
[[crates-io-publishing]]
crates = ["crate_name"]
workflow-filename = "release.yml"
environment = "publish"
```

check that it also contain the corresponding environment:
```
[[environments]]
name = "publish"
```

note that `publish` needs to match.

Example PR where we missed this: https://github.com/rust-lang/team/pull/2139/