platformio: switch to Arduono Framework with Staging version

due to a bug: SD_MMC library is missing

.gitlab-ci.yml

@@ -3,6 +3,7 @@ build:
   script:
 #    - platformio lib -g install 1
 #    - platformio ci --board=esp32thing
+    - platformio platform install https://github.com/platformio/platform-espressif32.git#feature/stage
     - platformio run
     - ln -s .pioenvs/esp32thing build
     - cp /home/user/.platformio/packages/framework-arduinoespressif32/tools/sdk/bin/bootloader.bin build/

platformio.ini

@@ -9,6 +9,9 @@
 ; http://docs.platformio.org/page/projectconf.html
 
 [env:esp32thing]
-platform = espressif32
+platform = espressif32_stage
 board = esp32thing
 framework = arduino
+;lib_deps =
+;  FS
+;  SD_MMC