fix: the global search keyboard event is not removed when the compone…

…nt is unmounted (#767)

#### What type of PR is this?
/kind bug

#### What this PR does / why we need it:


![image](https://user-images.githubusercontent.com/88016243/207133131-aa2404b1-c9d3-49fc-a1a7-949dd557e30c.png)

#### Which issue(s) this PR fixes:

Fixes halo-dev/halo#2927

#### Special notes for your reviewer:

#### Does this PR introduce a user-facing change?

```release-note
None
```

src/layouts/BasicLayout.vue

@@ -81,7 +81,7 @@ onMounted(() => {
 });
 
 onUnmounted(() => {
-  document.addEventListener("keydown", handleGlobalSearchKeybinding);
+  document.removeEventListener("keydown", handleGlobalSearchKeybinding);
 });
 
 // Generate menus by routes