Exclude .bumpversion.cfg from pre-commit checks

When creating new versions, the file is written back by `ConfigParser`.
Unfortunately, that includes trailing whitespace in some scenarios.
Exclude it from pre-commit checks as we have no way to guarantee its
formatting except that it's semantically correct for `ConfigParser`.

Author: dbnicholson

.pre-commit-config.yaml

@@ -1,4 +1,4 @@
-exclude: (\.git/|\.tox/|\.venv/|build/|static/|dist/|node_modules/)
+exclude: (\.git/|\.tox/|\.venv/|\.bumpversion.cfg$|build/|static/|dist/|node_modules/)
 repos:
 - repo: https://github.com/pre-commit/pre-commit-hooks
   rev: v2.0.0