Add Dependabot configuration for Python dependency management

[Copilot]

This PR adds a Dependabot configuration file to automate Python dependency updates for the repository.

Changes

Created .github/dependabot.yml with the following configuration:

• Package ecosystem: pip (monitors Python dependencies in pyproject.toml)
• Update schedule: Weekly checks for dependency updates
• Pull request limit: Up to 10 open PRs at a time

Benefits

• Security: Automatically receive notifications and PRs for security vulnerabilities in dependencies
• Maintenance: Keep dependencies up-to-date with minimal manual effort
• Compatibility: Early detection of breaking changes in dependency updates
• Automation: Dependabot will automatically create pull requests when updates are available for dependencies like ply, rdflib, click, pyyaml, xmltodict, and uritools

How it works

Once merged, Dependabot will:

1. Check for updates to Python dependencies every week
2. Create pull requests for available updates
3. Include release notes and changelog information in the PR description
4. Allow maintainers to review and merge updates at their convenience

The configuration follows GitHub's official Dependabot documentation.

Original prompt

Create a dependabot file for python for this repo

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