Revert "stm32duino" package dependency

It's still required for DFU upload for stm32f103 targets

Resolves #855

Author: valeros

platform.json

@@ -306,6 +306,11 @@
       "owner": "platformio",
       "version": "~0.7.0"
     },
+    "tool-stm32duino": {
+      "optional": true,
+      "owner": "platformio",
+      "version": "~1.0.1"
+    },
     "tool-openocd": {
       "type": "uploader",
       "optional": true,

platform.py

@@ -76,6 +76,8 @@ def configure_default_packages(self, variables, targets):
             if board.startswith(("portenta", "opta", "nicla", "giga")):
                 dfu_package = "tool-dfuutil-arduino"
                 self.packages.pop("tool-dfuutil")
+            elif build_mcu.startswith("stm32f103"):
+                dfu_package = "tool-stm32duino"
             else:
                 self.packages.pop("tool-dfuutil-arduino")
             self.packages[dfu_package]["optional"] = False