Introduce workspace dependencies (#12043)

# Description
This PR introduces [workspaces
dependencies](https://doc.rust-lang.org/cargo/reference/workspaces.html#the-dependencies-table).
The advantages are:
- a single place where dependency versions are declared
- reduces the number of files to change when upgrading a dependency
- reduces the risk of accidentally depending on 2 different versions of
the same dependency

I've only done a few so far. If this PR is accepted, I might continue
and progressively do the rest.

# User-Facing Changes
N/A

# Tests + Formatting
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting
N/A

crates/nu-system/Cargo.toml

@@ -14,11 +14,11 @@ bench = false
 
 [dependencies]
 libc = "0.2"
-log = "0.4"
-sysinfo = "0.30"
+log = { workspace = true }
+sysinfo = { workspace = true }
 
 [target.'cfg(target_family = "unix")'.dependencies]
-nix = { version = "0.27", default-features = false, features = ["fs", "term", "process", "signal"] }
+nix = { workspace = true, default-features = false, features = ["fs", "term", "process", "signal"] }
 
 [target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
 procfs = "0.16"
@@ -28,9 +28,9 @@ libproc = "0.14"
 mach2 = "0.4"
 
 [target.'cfg(target_os = "windows")'.dependencies]
-chrono = { version = "0.4", default-features = false, features = ["clock"] }
+chrono = { workspace = true, default-features = false, features = ["clock"] }
 ntapi = "0.4"
-once_cell = "1.18"
+once_cell = { workspace = true }
 windows = { version = "0.52", features = [
   "Wdk_System_SystemServices",
   "Wdk_System_Threading",