Automatically update the version in manifest.json at the time of publish.

[eucyt]

If #175 is merged, the version of mcp-server specified in manifest.json will be used.
Let's ensure that this version is also automatically updated when releasing.

This has already been handled in other relevant sections.
https://github.com/line/line-bot-mcp-server/blob/main/.github/scripts/update-version.mjs