Prepare changelog for release

has2k1 · has2k1 · commit 5ee0ed60b134 · 2023-05-09T19:06:19.000+03:00
Botched previous release. Tagged and released v0.12.0 instead of
v0.11.0.

Officially v0.11.0 has been skipped.
diff --git a/doc/changelog.rst b/doc/changelog.rst
@@ -3,7 +3,7 @@
 Changelog
 =========
 
-v0.11.0
+v0.12.1
 -------
 (2023-05-09)
 
