Bump README listed latest versions

Update README table to reflect new latest versions for branches: main 0.2.20 -> 0.2.21 and 1.x 0.1.20 -> 0.1.21. Documentation-only change to indicate released patch versions.

Author: mercyblitz

README.md

@@ -110,8 +110,8 @@ Choose the version that matches your Spring Boot generation:
 
 | Branch | Spring Boot Compatibility | Latest Version |
 |--------|---------------------------|----------------|
-| `main` | 3.0.x – 3.5.x, 4.0.x      | `0.2.20`       |
-| `1.x`  | 2.0.x – 2.7.x             | `0.1.20`       |
+| `main` | 3.0.x – 3.5.x, 4.0.x      | `0.2.21`       |
+| `1.x`  | 2.0.x – 2.7.x             | `0.1.21`       |
 
 ### Add Module Dependencies