Update Rust crate base64 to v0.21.4

This MR contains the following updates:

Package	Type	Update	Change
base64	dependencies	minor	0.13 -> 0.21
base64	dependencies	minor	0.13.1 -> 0.21.4

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Release Notes

marshallpierce/rust-base64 (base64)

v0.21.4

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• Make encoded_len const, allowing the creation of arrays sized to encode compile-time-known data lengths

v0.21.3

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• Implement source instead of cause on Error types
• Roll back MSRV to 1.48.0 so Debian can continue to live in a time warp
• Slightly faster chunked encoding for short inputs
• Decrease binary size

v0.21.2

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• Rollback MSRV to 1.57.0 -- only dev dependencies need 1.60, not the main code

v0.21.1

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• Remove the possibility of panicking during decoded length calculations
• DecoderReader no longer sometimes erroneously ignores padding #​226

Breaking changes

• Engine.internal_decode return type changed
• Update MSRV to 1.60.0

v0.21.0

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Migration

Functions

< 0.20 function	0.21 equivalent
encode()	engine::general_purpose::STANDARD.encode() or prelude::BASE64_STANDARD.encode()
encode_config()	engine.encode()
encode_config_buf()	engine.encode_string()
encode_config_slice()	engine.encode_slice()
decode()	engine::general_purpose::STANDARD.decode() or prelude::BASE64_STANDARD.decode()
decode_config()	engine.decode()
decode_config_buf()	engine.decode_vec()
decode_config_slice()	engine.decode_slice()

The short-lived 0.20 functions were the 0.13 functions with config replaced with engine.

Padding

If applicable, use the preset engines engine::STANDARD, engine::STANDARD_NO_PAD, engine::URL_SAFE, or engine::URL_SAFE_NO_PAD. The NO_PAD ones require that padding is absent when decoding, and the others require that canonical padding is present .

If you need the < 0.20 behavior that did not care about padding, or want to recreate < 0.20.0's predefined Configs precisely, see the following table.

0.13.1 Config	0.20.0+ alphabet	encode_padding	decode_padding_mode
STANDARD	STANDARD	true	Indifferent
STANDARD_NO_PAD	STANDARD	false	Indifferent
URL_SAFE	URL_SAFE	true	Indifferent
URL_SAFE_NO_PAD	URL_SAFE	false	Indifferent

v0.20.0

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Breaking changes

• Update MSRV to 1.57.0
• Decoding can now either ignore padding, require correct padding, or require no padding. The default is to require correct padding.
  • The NO_PAD config now requires that padding be absent when decoding.

0.20.0-alpha.1

Breaking changes

• Extended the Config concept into the Engine abstraction, allowing the user to pick different encoding / decoding implementations.
  • What was formerly the only algorithm is now the FastPortable engine, so named because it's portable (works on any CPU) and relatively fast.
  • This opens the door to a portable constant-time implementation (#​153, presumably ConstantTimePortable?) for security-sensitive applications that need side-channel resistance, and CPU-specific SIMD implementations for more speed.
  • Standard base64 per the RFC is available via DEFAULT_ENGINE. To use different alphabets or other settings ( padding, etc), create your own engine instance.
• CharacterSet is now Alphabet (per the RFC), and allows creating custom alphabets. The corresponding tables that were previously code-generated are now built dynamically.
• Since there are already multiple breaking changes, various functions are renamed to be more consistent and discoverable.
• MSRV is now 1.47.0 to allow various things to use const fn.
• DecoderReader now owns its inner reader, and can expose it via into_inner(). For symmetry, EncoderWriter can do the same with its writer.
• encoded_len is now public so you can size encode buffers precisely.

v0.13.1

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• More precise decode buffer sizing, avoiding unnecessary allocation in decode_config.

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