fix UTF-8 issue

.circleci/config.yml

@@ -139,6 +139,8 @@ jobs:
     steps:
       - *restore_repo_cache
       - *install_tox
+      - *install_wave
+      - *install_ffprobe
       - run: tox -e test_galaxy_packages
   js_unit:
     docker:

lib/galaxy/datatypes/media.py

@@ -12,7 +12,7 @@ from galaxy.util import which
 
 
 def ffprobe(path):
-    data = json.loads(subprocess.check_output(['ffprobe', '-loglevel', 'quiet', '-show_format', '-show_streams', '-of', 'json', path]))
+    data = json.loads(subprocess.check_output(['ffprobe', '-loglevel', 'quiet', '-show_format', '-show_streams', '-of', 'json', path]).decode("utf-8"))
     return data['format'], data['streams']