Drop "stage" suffix from @platformio dev/platform

Author: ivankravets

.travis.yml

@@ -36,7 +36,7 @@ script:
  - echo -e "travis_fold:start:platformio_test_env_prepare"
  - pip install -U https://github.com/platformio/platformio/archive/develop.zip
  - platformio platform install https://github.com/platformio/platform-espressif32.git#feature/stage
- - sed -i 's/https:\/\/github\.com\/espressif\/arduino-esp32\.git/*/' ~/.platformio/platforms/espressif32_stage/platform.json
+ - sed -i 's/https:\/\/github\.com\/espressif\/arduino-esp32\.git/*/' ~/.platformio/platforms/espressif32/platform.json
  - ln -s $TRAVIS_BUILD_DIR ~/.platformio/packages/framework-arduinoespressif32
  - echo -e "travis_fold:end:platformio_test_env_prepare"
  - echo -e "travis_fold:start:platformio_test"