chore: missing git tag for ic-cdk v0.20.1 release

Summary

The ic-cdk v0.20.1 release (2026-04-20) is published on crates.io but has no corresponding git tag in this repository. Every prior release from 0.15.0 through 0.19.0 has a plain semver git tag, so this appears to be an unintentional omission in the release process.

The release commit is:

317f55c feat: ic0 v1.1.0 and ic-cdk v0.20.1 with msg_caller_info_{data,signer} APIs (#708)

Why this matters

Projects that pin dfinity/cdk-rs as a git submodule (e.g. documentation repos, tooling, downstream consumers) rely on version tags to identify the correct commit to check out. Without a tag:

• Automated tooling that resolves "latest release" via git ls-remote --tags returns 0.19.0 instead of 0.20.1
• Maintainers who search for the release commit by tag come up empty and may incorrectly conclude the API has not shipped yet
• The gap between crates.io state and git state causes confusion about what is actually available to users

In this specific case: dfinity/developer-docs uses cdk-rs as a pinned submodule to verify Rust API examples against source. The missing tag caused us to initially conclude that msg_caller_info_data/msg_caller_info_signer were unreleased, when they had in fact shipped.

Request

Please push the 0.20.1 tag pointing to 317f55c (or the appropriate release commit):

git tag 0.20.1 317f55c
git push origin 0.20.1

Start by inspecting the existing semver tags and verify that commit 317f55c is the ic-cdk v0.20.1 release commit. Create and push the missing 0.20.1 tag, then confirm it appears in the repository's remote tags and points to the requested commit.