Bump MimeKit from 2.15.1 to 3.2.0

[dependabot]

Bumps MimeKit from 2.15.1 to 3.2.0.

Changelog

Sourced from MimeKit's changelog.

MimeKit 3.2.0 (2022-03-26)

• Rewrote QuotedPrintableEncoder to more strictly fold at the specified line length. (issue #781)
• Change the default maxLineLength for quoted-printable/base64 encoders to 76 to match the recommendation in the specification (was previously 72).
• Use cached Task instances (e.g. Task.CompletedTask) when possible to improve performance.
• Make use of ReadOnlySpan<T> instead of String.Substring() wherever possible to improve performance.
• Reduced string allocations in other ways.
• Provide MailboxAddress accessors for LocalPart and Domain. (issue #766)
• Replaced support for .NET Framework v4.6 with 4.6.1 and added a System.Text.Encoding.CodePages dependency to solve various cases where MimeKit would fail to initialize properly on ASP.NET systems using net461 when system character encodings were not available.
• Fixed MessagePartial to use invariant culture when setting number/total param values.
• Make sure all int.TryParse() calls use the correct NumberStyles.
• Make use of a ValueStringBuilder to construct strings without needing to allocate a StringBuilder.
• Fixed InternetAddressList.TryParse() to fail on invalid input. (issue #762)
• Added dispose handling to MimeMessage.CreateFromMailMessage().
• Improved MIME structure returned by TnefPart.ConvertToMessage().
• Rewrote header folding logic to avoid string allocations.
• Implemented IEquatable<T> on TnefNameId.
• If iso-8859-1 isn't available, fall back to ASCII instead of Windows-1252. (issue #751)

Special Thanks to Jason Nelson for taking the lead on many of the listed (and unlisted) performance improvements and helping me make MimeKit even more awesome!

MimeKit 3.1.1 (2022-01-30)

• When initializing character encodings for netstandard and net50/net60, wrap the Reflection logic to invoke System.Text.Encoding.RegisterProvider() in a try/catch to prevents exceptions when using the netstandard version of MimeKit in a .NET Framework app. (issue #751)
• Added a work-around for Office365 message/delivery-status parts where all status groups after the first are base64 encoded. This seems to be a bug in Office365 where it treats the first status group as MIME entity and the following status groups as the content. (issue #250)
• Fixed the MimeMessage .ctor that takes object parameters to first check that a Message-Id header was not supplied before generating one for the message. (issue #747)
• Fixed the BestEncodingFilter logic such that if any line in binary content is > 998 and it contains nul bytes, it should recommend base64 (not quoted-printable).

MimeKit 3.1.0 (2022-01-14)

• Always use a lowercase domain name in the Message-Id to work around bugs in eM Client. (issue #734)
• Improved handling of parsing Content-Types like "multipart/multipart/mixed; boundary=...".

... (truncated)

Commits

• 4de3405 Bumped version to 3.2.0
• 15e5de8 Bump nunit from 3.13.2 to 3.13.3
• 7da6fd2 Improved docs for QuotedPrintableDecoder .ctor
• a8f6061 Revert Base64Decoder performance improvements
• b497506 Get rid of unnecessary length check in Base64Encoder
• e6a4a92 Removed unnecessary code in QuotedPrintableEncoder
• 792cbd2 minor benchmark improvements
• 954246a Improved performance of the Base64Decoder
• c67c549 Rewrote QuotedPrintableEncoder to more strictly fold at the specified line le...
• 0e080c0 Get rid of unused code in the QuotedPrintableEncoder.Flush() method
• Additional commits viewable in compare view

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[dependabot]

Superseded by #85.