Update pip command

Author: winterheart

.travis.yml

@@ -15,8 +15,8 @@ addons:
       - libasound2-dev:i386 libpulse-dev:i386 libglib2.0-dev:i386
 
 install:
-  - pip3 install --upgrade pip
-  - pip3 install conan
+  - pip install --upgrade pip
+  - pip install conan
   - conan user
   - conan remote add bincrafters https://api.bintray.com/conan/bincrafters/public-conan