docs: Minor formatting typo in F401 example. (#11601)

## Summary

Removed stray space in sample code snippet that is against ruff's own
default formatting rules.

This documentation appears on
https://docs.astral.sh/ruff/rules/unused-import/

## Test Plan

This is a trivially obvious change, verifiable with `ruff format
--check`

crates/ruff/tests/snapshots/integration_test__rule_f401.snap

@@ -41,7 +41,7 @@ interface, as in:
 # __init__.py
 import some_module
 
-__all__ = [ "some_module"]
+__all__ = ["some_module"]
 ```
 
 ## Fix safety

crates/ruff_linter/src/rules/pyflakes/rules/unused_import.rs

@@ -54,7 +54,7 @@ enum UnusedImportContext {
 /// # __init__.py
 /// import some_module
 ///
-/// __all__ = [ "some_module"]
+/// __all__ = ["some_module"]
 /// ```
 ///
 /// ## Fix safety