fix: add readme field for PyPI project description

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Change-Id: I4111cae339ff4d21731fec3fab539269277f0218
Claude-Session-Id: b0a3e393-05a6-4967-ab25-0d2a6fd26558

Author: jd

pyproject.toml

@@ -6,6 +6,7 @@ build-backend = "hatchling.build"
 name = "alembic-git-revisions"
 dynamic = ["version"]
 description = "Automatic Alembic migration chaining based on git commit history"
+readme = "README.md"
 requires-python = ">=3.11"
 license = "Apache-2.0"
 classifiers = [