Explicitly set newline when rewriting for release (#7600)

tools/automation/release/__init__.py

@@ -3,7 +3,6 @@
 These are written according to the order they are called in.
 """
 
-import io
 import os
 import subprocess
 from typing import List, Optional, Set
@@ -70,7 +69,7 @@ def generate_authors(filename: str) -> None:
     authors = get_author_list()
 
     # Write our authors to the AUTHORS file
-    with io.open(filename, "w", encoding="utf-8") as fp:
+    with open(filename, "w", encoding="utf-8", newline="\n") as fp:
         fp.write(u"\n".join(authors))
         fp.write(u"\n")
 
@@ -90,7 +89,7 @@ def update_version_file(version: str, filepath: str) -> None:
         content = list(f)
 
     file_modified = False
-    with open(filepath, "w", encoding="utf-8") as f:
+    with open(filepath, "w", encoding="utf-8", newline="\n") as f:
         for line in content:
             if line.startswith("__version__ ="):
                 f.write('__version__ = "{}"\n'.format(version))