Rollback python-magic, default version is broken on magic 5.09

.travis.yml

@@ -30,7 +30,7 @@ install:
     - popd
     - pip install lxml
     - pip install officedissector
-    - pip install python-magic
+    - pip install git+https://github.com/Rafiot/python-magic.git@travis
     - if [ $(python -c 'import sys; print(sys.version_info.major)') == '2' ]; then pip install oletools olefile ; fi
     - pip install coveralls
     - pip install codecov