Resolve "uproot4 integration"

Closes #58 (closed)

km3io/gseagen.py

@@ -10,6 +10,7 @@ from .tools import cached_property
 
 class GSGReader(EventReader):
     """reader for gSeaGen ROOT files"""
+
     event_path = "Events"
     skip_keys = ["Header"]
 
@@ -25,7 +26,7 @@ class GSGReader(EventReader):
                         v = v.decode("utf-8")
                     except UnicodeDecodeError:
                         pass
-                header[k.decode("utf-8")] = v
+                header[k] = v
             return header
         else:
             warnings.warn("Your file header has an unsupported format")