chore(tvix/cargo): add dirs dependency

This crate provides sensible default locations for directories on
different platforms.

Change-Id: I0b61cc7f626dc6c8df903ba0f873be24e07d69b5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6170
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

tvix/eval/Cargo.lock

@@ -201,6 +201,15 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "dirs"
+version = "4.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca3aa72a6f96ea37bbc5aa912f6788242832f75369bdfdadcb0e38423f100059"
+dependencies = [
+ "dirs-sys",
+]
+
 [[package]]
 name = "dirs-next"
 version = "2.0.0"
@@ -211,6 +220,17 @@ dependencies = [
  "dirs-sys-next",
 ]
 
+[[package]]
+name = "dirs-sys"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b1d1d91c932ef41c0f2663aa8b0ca0342d444d842c06914aa0a7e352d0bada6"
+dependencies = [
+ "libc",
+ "redox_users",
+ "winapi",
+]
+
 [[package]]
 name = "dirs-sys-next"
 version = "0.1.2"
@@ -813,6 +833,7 @@ name = "tvix-eval"
 version = "0.1.0"
 dependencies = [
  "criterion",
+ "dirs",
  "rnix",
  "rustyline",
  "smol_str",

tvix/eval/Cargo.toml

@@ -9,6 +9,7 @@ edition = "2021"
 rnix = "0.10.2"
 smol_str = "0.1"
 rustyline = "10.0.0"
+dirs = "4.0.0"
 
 [dev-dependencies]
 criterion = "0.3.6"