Switch to bump-my-version for versioning updates

CONTRIBUTING.rst

@@ -8,14 +8,14 @@ Releasing a new version
 -----------------------
 
 To simplify updating the version number consistently across different files
-and creating the appropriate annotated tag, we use bump2version_. For a new
+and creating the appropriate annotated tag, we use bump-my-version_. For a new
 patch release, run ::
 
-    bump2version patch
+    bump-my-version bump patch
 
 and for a minor release ::
 
-    bump2version minor
+    bump-my-version bump minor
 
 Remember to also push the release tag with ``git push --tags``.
 
@@ -24,5 +24,5 @@ Use twine_ to upload the new release to PyPI.
 .. _GitHub: https://github.com/kynan/nbstripout
 .. _bug reports: https://github.com/kynan/nbstripout/issues
 .. _pull requests: https://github.com/kynan/nbstripout/pulls
-.. _bump2version: https://github.com/c4urself/bump2version
+.. _bump-my-version: https://github.com/callowayproject/bump-my-version
 .. _twine: https://twine.readthedocs.io/en/latest/#using-twine