Fix: Fix type hints for pretty_print function

The file can be str or bytes IO. For example sys.stdout is str IO
(TextIO).

gvm/xml.py

@@ -5,7 +5,7 @@
 
 import sys
 from io import IOBase
-from typing import List, Optional, Union
+from typing import List, Optional, TextIO, Union
 
 import defusedxml.lxml as secET
 from defusedxml import DefusedXmlException
@@ -68,7 +68,7 @@ def __init__(self, name):
 
 def pretty_print(
  xml: Union[str, List[Union[Element, str]], Element],
- file: IOBase = sys.stdout,
+ file: Union[TextIO, IOBase] = sys.stdout,
 ):
  """Prints beautiful XML-Code
 
@@ -85,9 +85,9 @@ def pretty_print(
  A IOBase type. Can be a File, StringIO, ...
 
  """
- if not isinstance(file, IOBase):
+ if not isinstance(file, (IOBase, TextIO)):
  raise TypeError(
- f"Type needs to be from IOBase, not {type(file)}."
+ f"Type needs to be from IOBase or TextIO, not {type(file)}."
  ) from None
 
  if isinstance(xml, list):