Update base64 requirement from 0.13 to 0.20

[dependabot]

Updates the requirements on base64 to permit the latest version.

Changelog

Sourced from base64's changelog.

0.20.0

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.

0.13.1

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

0.13.0

• Config methods are const
• Added EncoderStringWriter to allow encoding directly to a String
• EncoderWriter now owns its delegate writer rather than keeping a reference to it (though refs still work)
  • As a consequence, it is now possible to extract the delegate writer from an EncoderWriter via finish(), which returns Result<W> instead of Result<()>. If you were calling finish() explicitly, you will now need to use let _ = foo.finish() instead of just foo.finish() to avoid a warning about the unused value.
• When decoding input that has both an invalid length and an invalid symbol as the last byte, InvalidByte will be emitted instead of InvalidLength to make the problem more obvious.

0.12.2

• Add BinHex alphabet

0.12.1

• Add Bcrypt alphabet

0.12.0

• A Read implementation (DecoderReader) to let users transparently decoded data from a b64 input source
• IMAP's modified b64 alphabet
• Relaxed type restrictions to just AsRef<[ut8]> for main encode*/decode* functions
• A minor performance improvement in encoding

0.11.0

• Minimum rust version 1.34.0

... (truncated)

Commits

• 9fcde48 v0.20.0
• 68919ae Merge pull request #202 from marshallpierce/mp/edition-2021
• f58f441 Also updated fuzzers
• d86e8c8 Update to edition 2021
• 766fbc9 Merge pull request #198 from marshallpierce/mp/invalid-padding
• 250323c More fuzzer fixes
• bcbc669 Minor cleanup
• 604a3ca fix fuzzers
• 0996b81 Merge branch 'master' into mp/invalid-padding
• 442a809 Merge pull request #197 from marshallpierce/mp/update-msrv
• Additional commits viewable in compare view

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