Update platformio/ststm32 to v19.4.0

Author: renovate[bot]

arch/stm32/stm32.ini

@@ -2,7 +2,7 @@
 extends = arduino_base
 platform =
   # renovate: datasource=custom.pio depName=platformio/ststm32 packageName=platformio/platform/ststm32
-  platformio/ststm32@19.3.0
+  platformio/ststm32@19.4.0
 platform_packages =
   # TODO renovate
   platformio/framework-arduinoststm32@https://github.com/stm32duino/Arduino_Core_STM32/archive/2.10.1.zip