fix: add missing intelhex

Author: kakopappa

.github/workflows/build-esp8266-esp32.yml

@@ -62,6 +62,8 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install --upgrade platformio
+    - name: Install intelhex dependency
+      run: pip install intelhex
     - name: Step 6 - Install library dependencies
       run: |
         pio pkg install -l "bblanchon/ArduinoJson" -l "links2004/WebSockets" -g