fix travis build

.travis.yml

@@ -10,7 +10,7 @@ addons:
       - cppcheck
 before_install:
 	- sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa
-    - sudo apt-get update -q
+	- sudo apt-get update -q
 	- sudo apt-get install -y gcc-arm-embedded
 script:
   - export CC=gcc-7