Replace $nu.home-path with ~ in env.nu file

src/cli/self_update.rs

@@ -454,7 +454,7 @@ the corresponding `env` file under {cargo_home}.
 This is usually done by running one of the following (note the leading DOT):
     . "{cargo_home}/env"            # For sh/bash/zsh/ash/dash/pdksh
     source "{cargo_home}/env.fish"  # For fish
-    source $"{cargo_home_nushell}/env.nu"  # For nushell
+    source "{cargo_home_nushell}/env.nu"  # For nushell
     source "{cargo_home}/env.tcsh"  # For tcsh
     . "{cargo_home}/env.ps1"        # For pwsh
     source "{cargo_home}/env.xsh"   # For xonsh

src/cli/self_update/env.nu

@@ -1,2 +1,2 @@
 use std/util "path add"
-path add $"{cargo_bin}"
+path add "{cargo_bin}"

src/cli/self_update/shell.rs

@@ -311,13 +311,13 @@ impl UnixShell for Nu {
 
     fn source_string(&self, process: &Process) -> Result<String> {
         Ok(format!(
-            r#"source $"{}/env.nu""#,
+            r#"source "{}/env.nu""#,
             self.cargo_home_str(process)?
         ))
     }
 
     fn cargo_home_str(&self, process: &Process) -> Result<Cow<'static, str>> {
-        cargo_home_str_with_home("($nu.home-path)", process)
+        cargo_home_str_with_home("~", process)
     }
 }