install adafruit-nrfutil for travis

Author: hathach

.travis.yml

@@ -12,6 +12,13 @@ env:
     - PRETTYNAME="Adafruit TinyUSB Library"
     #- DOXYFILE=$TRAVIS_BUILD_DIR/.doxyfile
 
+addons:
+  apt:
+    packages:
+      - python3
+      - python3-pip
+      - python3-setuptools
+      
 before_install:
     - wget -q https://raw.githubusercontent.com/adafruit/travis-ci-arduino/master/install.sh
     # add tinyusb option for m4
@@ -20,6 +27,7 @@ before_install:
 
 install:
     - arduino --install-library "Adafruit SPIFlash","Adafruit QSPI"
+    - pip3 install --user adafruit-nrfutil
 
 script:
     - build_m4_platforms