Bump version and changelog for release

Also add a `RELEASING.md` doc, which can record the procedure as it
changes over time. (e.g. releases driven via CI)

Author: sirosen

RELEASING.md

@@ -0,0 +1,7 @@
+Releasing nose2
+---------------
+
+- Update the version in `nose2/__init__.py`
+- Update `changelog.rst`
+- Commit changes
+- Run `make release`

docs/changelog.rst

@@ -5,12 +5,12 @@ nose2 uses semantic versioning (currently in 0.x) and the popular
 "keep a changelog" format (v1.0.0).
 
 nose2 tries not to break backwards compatibility in any release. Until v1.0,
-versions are numbered `0.MAJOR.MINOR`. Major releases introduce new
+versions are numbered ``0.MAJOR.MINOR``. Major releases introduce new
 functionality or contain necessary breaking changes. Minor releases are
 primarily used for bugfix or small features which are unlikely to break users'
 testsuites.
 
-0.13.0 (Unreleased)
+0.13.0 (2023-04-29)
 -------------------
 
 * Remove support for python2 and older python3 versions

nose2/__init__.py

@@ -1,5 +1,5 @@
 from nose2.main import discover, main
 
-__version__ = "0.12.0"
+__version__ = "0.13.0"
 
 __all__ = ("__version__", "discover", "main")