chore(deps): replace base64 with boring2::base64

[0x676e67]

On my machine, the boring2 base64 encoding implementation benchmarks faster than Rust’s base64. Replacing the implementation also reduces crate dependencies, which shortens compile time.

[Copilot]

Pull Request Overview

This PR replaces the base64 crate dependency with boring2::base64 for base64 encoding operations to improve performance and reduce compilation dependencies.

• Removes the base64 crate dependency from Cargo.toml
• Updates the basic_auth function implementation to use boring2::base64::encode_block
• Changes the function visibility from pub to pub(crate) and refactors the encoding logic

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/util.rs	Replaces base64 encoding implementation and updates function visibility
Cargo.toml	Removes base64 crate dependency

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