Increment version to 2.0.0a21 (#1679)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: bferguso

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "bcap"
-version = "2.0.0a20"
+version = "2.0.0a21"
 readme = "README.md"
 requires-python = ">=3.12"
 authors = []