Update Rust crate base64 to 0.23

[oxide-renovate]

This PR contains the following updates:

Package	Type	Update	Change
base64	workspace.dependencies	minor	0.22 → 0.23

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Release Notes

marshallpierce/rust-base64 (base64)

v0.23.0

Compare Source

• Added more consts for preconfigured configs and engines
• Make DecodeError::InvalidLastSymbol more clear by including the decoded value
• Added SIMD-accelerated engines behind the default-on simd-unsafe feature: Simd picks the best
  instruction set at runtime (AVX2 on x86_64, NEON on aarch64) and falls back to the scalar
  GeneralPurpose engine, while Avx2 and Neon target one instruction set with no runtime
  detection and work in no_std. The engines support the standard and URL-safe alphabets.
• Update MSRV to 1.71.0
• Add support for custom padding symbols

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