chore: update default theme package (halo-dev#2805)

#### What type of PR is this?

/kind improvement
/milestone 2.0

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

更新默认主题的安装包。 https://github.com/halo-dev/theme-earth/releases/tag/v1.0.0

#### Special notes for your reviewer:

测试方式：

1. 使用全新的环境启动此 PR。
2. 插件默认主题是否正确初始化。

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

```release-note
None
```