docs(bevy_workbench): update readme version references to 0.3

Author: Bli-AIk

readme.md

@@ -44,7 +44,7 @@ view, and menu bar panels.
 1. **Add to your `Cargo.toml`**:
    ```toml
    [dependencies]
-   bevy_workbench = "0.2"
+   bevy_workbench = "0.3"
    ```
 
 2. **Basic setup**:

readme_zh-hans.md

@@ -41,7 +41,7 @@
 1. **添加到 `Cargo.toml`**：
    ```toml
    [dependencies]
-   bevy_workbench = "0.2"
+   bevy_workbench = "0.3"
    ```
 
 2. **基本用法**：