Bump version to 3.12.1

Author: rmk135

docs/main/changelog.rst

@@ -7,8 +7,8 @@ that were made in every particular version.
 From version 0.7.6 *Dependency Injector* framework strictly 
 follows `Semantic versioning`_
 
-Development version
--------------------
+3.12.1
+------
 - Update main page example from "services_v1" to "services_v2".
 - Fix few typos on main page.
 - Add new example miniapp "password_hashing".

src/dependency_injector/__init__.py

@@ -1,6 +1,6 @@
 """Dependency injector top-level package."""
 
-__version__ = '3.12.0'
+__version__ = '3.12.1'
 """Version number that follows semantic versioning.
 
 :type: str