[rust] upgrade toml_edit (0.19.8 -> 0.20.4) and toml (0.7.3 -> 0.8.4)

Summary: Upgrading `toml_edit` from `0.19.8` to `0.20.4` and `toml` from `0.7.3` to `0.8.4`

Test Plan:
```
$ fbcode/common/rust/tools/scripts/third-party-check.sh
$ buck2 test fbcode//linttool/linttool/...
$ buck2 run fbcode//common/rust/cargo_from_buck/autocargo:autocargo
```

Reviewed By: zertosh

Differential Revision: D50616780

fbshipit-source-id: aa35720d2545de3315b64f0d2042b7e6cb328f50

antlir/util/cli/json_arg/Cargo.toml

@@ -18,7 +18,7 @@ path = "src/lib.rs"
 [dependencies]
 serde = { version = "1.0.185", features = ["derive", "rc"] }
 serde_json = { version = "1.0.100", features = ["float_roundtrip", "unbounded_depth"] }
-toml = "0.7.3"
+toml = "0.8.4"
 
 [dev-dependencies]
 clap = { version = "3.2.25", features = ["derive", "env", "regex", "unicode", "wrap_help"] }