Update RT_VER_NUM to 5.3.0

Rbb666 · Rbb666 · commit 929287400593 · 2025-12-11T16:58:30.000+08:00
diff --git a/src/Kconfig b/src/Kconfig
@@ -434,7 +434,7 @@ endif
 
 config RT_VER_NUM
     hex
-    default 0x50201
+    default 0x50300
     help
         RT-Thread version number
 
