Merge pull request adafruit#359 from adafruit/bump-version-1.7.15

bump up version to 1.7.15

Author: hathach

platform.txt

@@ -20,7 +20,7 @@
 # https://arduino.github.io/arduino-cli/0.33/platform-specification/
 
 name=Adafruit SAMD (32-bits ARM Cortex-M0+ and Cortex-M4) Boards
-version=1.7.14
+version=1.7.15
 
 # Compile variables
 # -----------------