Remove default STM32Cube package

Fixes platformio/platformio-core#3777

Author: valeros

platform.json

@@ -56,7 +56,6 @@
       "title": "Arduino"
     },
     "stm32cube": {
-      "package": "framework-stm32cube",
       "script": "builder/frameworks/stm32cube.py",
       "description": "STM32Cube embedded software libraries, including: The HAL hardware abstraction layer, enabling portability between different STM32 devices via standardized API calls; The Low-Layer (LL) APIs, a light-weight, optimized, expert oriented set of APIs designed for both performance and runtime efficiency",
       "homepage": "https://www.st.com/en/ecosystems/stm32cube.html",