[docs] Add release date of v0.21.1 to changelog.

seifertm · seifertm · commit 82b010d6869b · 2023-07-12T12:06:10.000+02:00
Signed-off-by: Michael Seifert &lt;m.seifert@digitalernachschub.de&gt;
diff --git a/docs/source/reference/changelog.rst b/docs/source/reference/changelog.rst
@@ -2,7 +2,7 @@
 Changelog
 =========
 
-0.22.0 (UNRELEASED)
+0.21.1 (2023-07-12)
 ===================
 - Output a proper error message when an invalid ``asyncio_mode`` is selected.
 - Extend warning message about unclosed event loops with additional possible cause.
