Bump MimeKit from 3.6.0 to 4.3.0

[dependabot]

Bumps MimeKit from 3.6.0 to 4.3.0.

Changelog

Sourced from MimeKit's changelog.

MimeKit 4.3.0 (2023-11-11)

• Added work-around for broken Message-ID header values of the form <id@@​domain>. (issue #962)
• Added virtual Multipart.TryGetValue(TextFormat, out TextPart) method that recursively iterates over child parts to find the TextPart with the desired format.
• Fixed MimeMessage.TextBody/HtmlBody to locate the text body in a multipart/mixed that is inside of a multipart/alternative. This resolves an issue locating the text body within some broken iOS Apple Mail messages. (issue #963)

MimeKit 4.2.0 (2023-09-02)

• Follow the spec more closely for allowable header field characters. (issue #936)
• Avoid throwing NRE when an RC2 algorithm was used for S/MIME w/o parameters. (issue #941)
• Added a few more (undocumented) TnefPropertyIds.
• Optimized AttachmentCollection.Add(byte[], ...) by not copying the data to a new stream.
• Improved performance of HtmlTokenizer.
• Added new HtmlTokenizer constructors that take a Stream instead of a TextReader. This allows for a slight performance improvement over using a TextReader as well.
• Lazy-allocate Base64/QuotedPrintable decoders when decoding rfc2047-encoded headers. This is a very small reduction in GC pressure.
• Reduced memory allocations in Rfc2047.DecodePhrase() and DecodeText().
• Avoid allocating empty List<string>s in DomainList.ctor(), lazily allocate the list only when a domain is added. Another minor reduction in GC pressure.
• Updated the Date parser to allocate an internal list of tokens with a optimal initial capacity to avoid the need for reallocating.

MimeKit 4.1.0 (2023-06-17)

• Readded the System.Net.Mail-to-MimeKit conversion APIs for the netstandard2.x frameworks. (issue #913)
• Fixed the MimeEntity.LoadAsync() overloads that take a ContentType parameter to to properly wait to dispose of the stream until after the entity has been parsed. (issue #916)
• Optimized conversion between HeaderId and string.
• Added a new IMimeParser interface that both MimeParser and ExperimentalMimePraser implement.
• Added "unicode" to the list of charset aliases for UTF-8. (issue #923)
• Added support for the Edwards Curve DSA PGP public key algorithm. (issue #932)
• Bumped System.Security.Cryptography.Pkcs dependency to 7.0.2.
• Bumped BouncyCastle dependency to 2.2.1.

MimeKit 4.0.0 (2023-04-15)

• Ported to BouncyCastle v2.1.1. (issue #865)
• Fixed System.Net.Mail.MailMessage -> MimeMessage converter to reset MailMessage attachment/alternateview streams back to 0 after copying them. (issue #907)

... (truncated)

Commits

• 760b4ee Bumped version to 4.3.0
• bcac1ef Bump nunit from 3.13.3 to 3.14.0
• c57f2c0 Bump BenchmarkDotNet from 0.13.9 to 0.13.10
• 5fb3b94 Added unit test for multipart/mixed within multipart/alternative
• 8324513 Added virtual Multipart.TryGetValue(TextFormat, out TextPart)
• 79046cd Work-around Message-IDs that are brokenly in the form <id@@​domain>
• 7dc832b Bump BenchmarkDotNet from 0.13.8 to 0.13.9
• df40fb5 Update main.yml
• 6d63a8d Add coveralls.net to the dotnet tools config
• 18237f3 Bump BenchmarkDotNet from 0.13.7 to 0.13.8
• Additional commits viewable in compare view

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[JoeShook]

@dependabot rebase.

[JoeShook]

@dependabot rebase

[dependabot]

OK, I won't notify you again about this release, but will get in touch when a new version is available. If you'd rather skip all updates until the next major or minor version, let me know by commenting @dependabot ignore this major version or @dependabot ignore this minor version. You can also ignore all major, minor, or patch releases for a dependency by adding an ignore condition with the desired update_types to your config file.

If you change your mind, just re-open this PR and I'll resolve any conflicts on it.