chore: bump version to v0.9.1

[QuantumGhost]

Bump version to v0.9.1.

The polling protocol is not official released. There should be no outside users of this protocol now.

Closes #352

Pull Request Checklist

Thank you for your contribution! Before submitting your PR, please make sure you have completed the following checks:

Compatibility Check

• I have checked whether this change affects the backward compatibility of the plugin declared in README.md
• I have checked whether this change affects the forward compatibility of the plugin declared in README.md
• If this change introduces a breaking change, I have discussed it with the project maintainer and specified the release version in the README.md
• I have described the compatibility impact and the corresponding version number in the PR description
• I have checked whether the plugin version is updated in the README.md

Available Checks

• just build has passed
• Relevant documentation has been updated (if necessary)

[gemini-code-assist]

Code Review

This pull request bumps the version of the dify-plugin package from 0.9.0 to 0.9.1 in both pyproject.toml and uv.lock. The reviewer suggested using single quotes instead of double quotes for the version string in pyproject.toml to maintain consistency with the rest of the file.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.