upgrade packages from toml-5 (0.5.8 fork) -> toml (0.7.3)

Summary:
The fixes bellow are because of one of 4 reasons:
1. [`toml::from_slice`](https://docs.rs/toml/0.5.8/toml/de/fn.from_slice.html) and [`toml::to_vec`](https://docs.rs/toml/0.5.8/toml/ser/fn.to_vec.html)  have been removed and replaced in the current version by [`toml::from_str`](https://docs.rs/toml/0.7.3/toml/fn.from_str.html) and [`toml::to_string`](https://docs.rs/toml/0.7.3/toml/fn.to_string.html)
2. [`toml::Spanned::span`](https://docs.rs/toml/0.7.3/toml/struct.Spanned.html#method.span) now returns a `Range<usize>` and not a `(usize, usize)` like it used to ([here](https://docs.rs/toml/0.5.8/toml/struct.Spanned.html#method.span))
3. The internal representation for parsed TOML via [`toml_edit`](https://docs.rs/toml_edit/latest/toml_edit/) uses `"` instead of `'` for representing string values
4. TOML parsing errors are now multi-line errors and need to be accounted for in tests

Reviewed By: zertosh, shayne-fletcher

Differential Revision: D45896591

fbshipit-source-id: 403790674c7449da9f7322d69ec3030369310aab

Author: diliop

below/config/Cargo.toml

@@ -15,7 +15,7 @@ btrfs = { package = "below-btrfs", version = "0.6.3", path = "../btrfs" }
 cgroupfs = { version = "0.6.3", path = "../cgroupfs" }
 once_cell = "1.12"
 serde = { version = "1.0.136", features = ["derive", "rc"] }
-toml = "=0.5.8"
+toml = "0.7.3"
 
 [dev-dependencies]
 tempdir = "0.3"

below/dump/Cargo.toml

@@ -23,4 +23,4 @@ slog = { version = "2.7", features = ["max_level_trace", "nested-values"] }
 store = { package = "below-store", version = "0.6.3", path = "../store" }
 tar = "0.4.38"
 tempdir = "0.3"
-toml = "=0.5.8"
+toml = "0.7.3"

below/view/Cargo.toml

@@ -25,7 +25,7 @@ render = { package = "below-render", version = "0.6.3", path = "../render" }
 serde = { version = "1.0.136", features = ["derive", "rc"] }
 slog = { version = "2.7", features = ["max_level_trace", "nested-values"] }
 store = { package = "below-store", version = "0.6.3", path = "../store" }
-toml = "=0.5.8"
+toml = "0.7.3"
 
 [dev-dependencies]
 tempdir = "0.3"