Update upgrade command to use shout package

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@because/shout",
-  "version": "0.0.6",
+  "version": "0.0.7",
   "description": "shell output tester",
   "module": "src/index.ts",
   "type": "module",

src/cli/index.ts

@@ -264,4 +264,16 @@ $ true
 [0]`)
   })
 
+program
+  .command("upgrade")
+  .description("Upgrade to the latest version")
+  .action(async () => {
+    const result = await Bun.spawn(["bun", "install", "-g", "@because/shout@latest"], {
+      stdin: "inherit",
+      stdout: "inherit",
+      stderr: "inherit",
+    }).exited
+    process.exit(result)
+  })
+
 program.parse()