Remove ref to deprecated .hex attribute

Signed-off-by: Michael Honaker <[email protected]>

oper8/vcs.py

@@ -112,7 +112,7 @@ def __init__(self, directory: str, create_if_needed: bool = False, **kwargs):
     @property
     def head(self) -> str:
         """Get a reference to the current HEAD"""
-        return self.repo.head.target.hex
+        return str(self.repo.head.target)
 
     def get_ref(self, refish: str) -> Tuple[Commit, Reference]:
         """Get a git commit and reference from a shorthand string