Upgrade the version to 2.12.1-dev0 following 2.12.0 release

Author: Pierre-Sassoulas

pylint/__pkginfo__.py

@@ -2,7 +2,7 @@
 # For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
 from typing import Tuple
 
-__version__ = "2.12.0"
+__version__ = "2.12.1-dev0"
 
 
 def get_numversion_from_version(v: str) -> Tuple:

tbump.toml

@@ -1,7 +1,7 @@
 github_url = "https://github.com/PyCQA/pylint"
 
 [version]
-current = "2.12.0"
+current = "2.12.1-dev0"
 regex = '''
 ^(?P<major>0|[1-9]\d*)
 \.