chore(deps): update rust crate base64 to 0.22

This PR contains the following updates:

Package	Type	Update	Change
base64	dependencies	minor	`0.21` -> `0.22`

Release Notes

marshallpierce/rust-base64 (base64)

### [`v0.22.0`](https://togithub.com/marshallpierce/rust-base64/blob/HEAD/RELEASE-NOTES.md#0220) [Compare Source](https://togithub.com/marshallpierce/rust-base64/compare/v0.21.7...v0.22.0) - `DecodeSliceError::OutputSliceTooSmall` is now conservative rather than precise. That is, the error will only occur if the decoded output *cannot* fit, meaning that `Engine::decode_slice` can now be used with exactly-sized output slices. As part of this, `Engine::internal_decode` now returns `DecodeSliceError` instead of `DecodeError`, but that is not expected to affect any external callers. - `DecodeError::InvalidLength` now refers specifically to the *number of valid symbols* being invalid (i.e. `len % 4 == 1`), rather than just the number of input bytes. This avoids confusing scenarios when based on interpretation you could make a case for either `InvalidLength` or `InvalidByte` being appropriate. - Decoding is somewhat faster (5-10%) ### [`v0.21.7`](https://togithub.com/marshallpierce/rust-base64/blob/HEAD/RELEASE-NOTES.md#0217) [Compare Source](https://togithub.com/marshallpierce/rust-base64/compare/v0.21.6...v0.21.7) - Support getting an alphabet's contents as a str via `Alphabet::as_str()` ### [`v0.21.6`](https://togithub.com/marshallpierce/rust-base64/blob/HEAD/RELEASE-NOTES.md#0216) [Compare Source](https://togithub.com/marshallpierce/rust-base64/compare/v0.21.5...v0.21.6) - Improved introductory documentation and example

Configuration

📅 Schedule: Branch creation - "every weekend" in timezone Asia/Tokyo, Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

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⚠ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

any of the package files in this branch needs updating, or
the branch becomes conflicted, or
you click the rebase/retry checkbox if found above, or
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The artifact failure details are included below:

File name: Cargo.lock

Command failed: cargo update --config net.git-fetch-with-cli=true --manifest-path Cargo.toml --package base64@0.21.5 --precise 0.22.0
    Updating crates.io index
error: failed to select a version for the requirement `base64 = "^0.21"`
candidate versions found which didn't match: 0.22.0
location searched: crates.io index
required by package `reqwest v0.11.23`
    ... which satisfies dependency `reqwest = "^0.11"` (locked to 0.11.23) of package `ichiyo_ai v2.4.0 (/tmp/renovate/repos/github/approvers/ichiyoAI)`
perhaps a crate was updated and forgotten to be re-vendored?

approvers / ichiyoAI