Merge pull request espressif#70 from adafruit/avr_dep

fixing missing arduino:avr dep for adafruit:avr

Author: siddacious

build_platform.py

@@ -97,6 +97,8 @@ def install_platform(platform):
     print("Installing", platform, end=" ")
     if platform == "adafruit:samd":   # we have a platform dep
         install_platform("arduino:samd")
+    if platform == "adafruit:avr":   # we have a platform dep
+        install_platform("arduino:avr")
     if os.system("arduino-cli core install "+platform+" --additional-urls "+BSP_URLS+" > /dev/null") != 0:
         ColorPrint.print_fail("FAILED to install "+platform)
         exit(-1)