fix: close temporary file after creating it.

This fixes "The process cannot access the file
because it is being used by another process"
errors on Windows.

The file is still automatically deleted by the
`os.unlink` call later in the function.

Updates #5606
Fixes #5642

backend/open_webui/apps/webui/utils.py

@@ -87,7 +87,7 @@ def load_toolkit_module_by_id(toolkit_id, content=None):
     # Create a temporary file and use it to define `__file__` so
     # that it works as expected from the module's perspective.
     temp_file = tempfile.NamedTemporaryFile(delete=False)
-
+    temp_file.close()
     try:
         with open(temp_file.name, "w", encoding="utf-8") as f:
             f.write(content)
@@ -131,6 +131,7 @@ def load_function_module_by_id(function_id, content=None):
     # Create a temporary file and use it to define `__file__` so
     # that it works as expected from the module's perspective.
     temp_file = tempfile.NamedTemporaryFile(delete=False)
+    temp_file.close()
     try:
         with open(temp_file.name, "w", encoding="utf-8") as f:
             f.write(content)