Rebase Pyink to psf@226cbf0.

Noticeable style changes:

1. Parenthesize multiple context managers psf#3489.

The following style changes are temporarily disabled when `--preview` is used together with `--pyink`:

2. Format unicode escape sequences psf#2916.
3. Parenthesize conditional expressions psf#2278.

PiperOrigin-RevId: 507485670

README.md

@@ -103,6 +103,11 @@ patches as possible in the future.
 *   Module docstrings are formatted same as other docstrings (see
     [psf/black#3493](https://github.com/psf/black/issues/3493)).
 
+*   Temporarily disabled the following _Black_ future style changes:
+
+    *   https://github.com/psf/black/pull/2916
+    *   https://github.com/psf/black/pull/2278
+
 ## Historical differences
 
 These are differences that existed in the past. We have upstreamed them to