fix: use /c instead of -c on windows in postinstall hook

src/backend/mod.rs

@@ -550,7 +550,7 @@ pub trait Backend: Debug + Send + Sync {
             .env(&*env::PATH_KEY, plugins::core::path_env_with_tv_path(tv)?)
             .env("MISE_TOOL_INSTALL_PATH", tv.install_path())
             .with_pr(&ctx.pr)
-            .arg("-c")
+            .arg(env::SHELL_COMMAND_FLAG)
             .arg(script)
             .envs(self.exec_env(&ctx.config, &ctx.ts, tv).await?)
             .execute()?;

src/cli/exec.rs

@@ -214,13 +214,10 @@ fn parse_command(
             let (program, args) = command.split_first().unwrap();
             (program.clone(), args.into())
         }
-        _ => {
-            #[cfg(unix)]
-            let command_flag = "-c";
-            #[cfg(windows)]
-            let command_flag = "/c";
-            (shell.into(), vec![command_flag.into(), c.clone().unwrap()])
-        }
+        _ => (
+            shell.into(),
+            vec![env::SHELL_COMMAND_FLAG.into(), c.clone().unwrap()],
+        ),
     }
 }
 

src/env.rs

@@ -31,6 +31,10 @@ pub static MISE_SHELL: Lazy<Option<ShellType>> = Lazy::new(|| {
         .parse()
         .ok()
 });
+#[cfg(unix)]
+pub static SHELL_COMMAND_FLAG: &str = "-c";
+#[cfg(windows)]
+pub static SHELL_COMMAND_FLAG: &str = "/c";
 
 // paths and directories
 #[cfg(test)]