🔧 Adapt type hinting to Python 3.9 compatibility

src/qe_tools/outputs/base.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 """Base parser for the outputs of Quantum ESPRESSO."""
 
+from typing import Union
 import abc
 
 
@@ -9,7 +10,7 @@ class BaseOutput(abc.ABC):
     Abstract class for the outputs of Quantum ESPRESSO.
     """
 
-    def __init__(self, outputs: dict | None = None, executable: str | None = None):
+    def __init__(self, outputs: Union[dict, None] = None, executable: str | None = None):
         self.outputs = outputs
         self.executable = executable
 

src/qe_tools/outputs/pw.py

@@ -12,7 +12,7 @@
 class PwOutput(BaseOutput):
     """Output of the Quantum ESPRESSO pw.x code."""
 
-    def __init__(self, outputs: dict | None = None):
+    def __init__(self, outputs: Union[dict, None] = None):
         super().__init__(outputs=outputs, executable='pw.x')
 
     @classmethod
@@ -42,7 +42,7 @@ def from_dir(cls, directory: Union[str, Path], filetype: str = 'both'):
 
             if filetype in ['both', 'xml']:
                 if file.suffix == '.xml':
-                    parser_xml = PwXMLParser.from_file(filename=file)
+                    parser_xml = PwXMLParser.from_file(filename=file.as_posix())
                     parser_xml.parse()
                     d_out_xml = parser_xml.dict_out