shellexpand: upgrade to shellexpand v3

shellexpand now requires that the home_dir context function returns
an Option<String> rather than an Option<std::path::Path>.

Upgrade the shellexpand crate and garden API usage accordingly.

Cargo.toml

@@ -37,7 +37,7 @@ is-terminal = "0.4.10"
 pathdiff = "0.2.1"
 rayon = "1.8.0"
 rm_rf = "0.6.2"
-shellexpand = "2.1.2"
+shellexpand = { version = "3.1.0", features = ["full"] }
 shell-words = "1.1.0"
 shlex = "1.2.0"
 strum = "0.25.0"

src/eval.rs

@@ -181,12 +181,12 @@ fn expand_graft_vars(
 }
 
 /// Resolve ~ to the current user's home directory
-fn home_dir() -> Option<std::path::PathBuf> {
+fn home_dir() -> Option<String> {
     // Honor $HOME when set in the environment.
     if let Ok(home) = std::env::var("HOME") {
-        return Some(std::path::PathBuf::from(home));
+        return Some(home);
     }
-    dirs::home_dir()
+    dirs::home_dir().map(|x| x.to_string_lossy().to_string())
 }
 
 /// Resolve an expression in a garden/tree/global scope