Update Rust crate base64 to ^0.21.5

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
base64	dependencies	patch	^0.21.3 -> ^0.21.5

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Release Notes

marshallpierce/rust-base64 (base64)

### [`v0.21.5`](https://togithub.com/marshallpierce/rust-base64/blob/HEAD/RELEASE-NOTES.md#0215) [Compare Source](https://togithub.com/marshallpierce/rust-base64/compare/v0.21.4...v0.21.5) - Add `Debug` and `Clone` impls for the general purpose Engine ### [`v0.21.4`](https://togithub.com/marshallpierce/rust-base64/blob/HEAD/RELEASE-NOTES.md#0214) [Compare Source](https://togithub.com/marshallpierce/rust-base64/compare/v0.21.3...v0.21.4) - Make `encoded_len` `const`, allowing the creation of arrays sized to encode compile-time-known data lengths

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Configuration

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