remote: Fix more quoting issues with nushell (#41547)

https://github.com/zed-industries/zed/pull/40084#issuecomment-3464159871
Closes https://github.com/zed-industries/zed/pull/41547

Release Notes:

- Fixed remoting not working when the remote has nu set as its shell

crates/languages/src/python.rs

@@ -1211,7 +1211,7 @@ impl ToolchainLister for PythonToolchainProvider {
                 activation_script.extend(match shell {
                     ShellKind::Fish => Some(format!("\"{pyenv}\" shell - fish {version}")),
                     ShellKind::Posix => Some(format!("\"{pyenv}\" shell - sh {version}")),
-                    ShellKind::Nushell => Some(format!("\"{pyenv}\" shell - nu {version}")),
+                    ShellKind::Nushell => Some(format!("^\"{pyenv}\" shell - nu {version}")),
                     ShellKind::PowerShell => None,
                     ShellKind::Csh => None,
                     ShellKind::Tcsh => None,