Bump version to 3.1.2

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jochenchrist

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "open-data-contract-standard"
-version = "3.1.1" # in sync with spec
+version = "3.1.2" # in sync with spec
 description = "The Pydantic Model of the Open Data Contract Standard"
 readme = "README.md"
 authors = [