package: replace open(fn, 'w').close() by open(fn, 'wb').close()

We don't need to open the files in text mode just to create them (or update
their modification time).
diff --git a/Lib/packaging/util.py b/Lib/packaging/util.py
index 348e3cd..058f13e 100644
--- a/Lib/packaging/util.py
+++ b/Lib/packaging/util.py
@@ -1201,7 +1201,7 @@
     if requested:
         requested_path = distinfo['requested_path']
         logger.info('creating %s', requested_path)
-        open(requested_path, 'w').close()
+        open(requested_path, 'wb').close()
         distinfo['installed'].append(requested_path)
 
     record_path = distinfo['record_path']