| syntax changed to Union for older python versions

Author: arnavdas88

nats/contrib/claims/models.py

@@ -19,7 +19,7 @@ class Claims(FlatteningModel):
 
     # Nats Data
     nats: Optional[Union[User, Account, Operator]]
-    issuer_account: Optional[str | bytes]
+    issuer_account: Optional[Union[str, bytes]]
 
     def __init__(
         self,
@@ -31,7 +31,7 @@ def __init__(
         nbf: Optional[int] = None,
         sub: Optional[str] = None,
         nats: Optional[Union[User, Account, Operator]] = None,
-        issuer_account: Optional[str | bytes] = None,
+        issuer_account: Optional[Union[str, bytes]] = None,
     ):
         self.exp: Optional[int] = exp
         self.jti: Optional[str] = jti