Bump MimeKit from 4.11.0 to 4.12.0

[dependabot]

Bumps MimeKit from 4.11.0 to 4.12.0.

Changelog

Sourced from MimeKit's changelog.

MimeKit 4.12.0 (2025-04-28)

• Removed CTRL characters from the list of allowed domain characters.
• Fixed a bug in the address list parser in Strict mode that allowed 2 addresses to be separated by whitespace instead of requiring a comma.
• Added a new MimeAnonymizer class that can be used to anonymize MimeMessages by x-ing out non-syntactically relevant information.
• Fixed TryParse methods to not throw ArgumentExceptions. (issue #1158)
• Fixed a bug in MimeReader that used the buffer offset instead of the stream offset to check if the stream position was beyond the byte offset specified by a Content-Length header when parsing UNIX mbox files.
• Fixed a long-standing bug in MimeParser (which also existed in MimeReader) where it would encounter a buffering bug when parsing some Mbox files (typically multi-gigabyte). (issue #991)
• Fixed AttachmentCollection.Add/AddAsync methods to dispose the MimePart it is creating if loading content fails from the stream fails.
• Added leaveOpen parameters for HtmlWriter .ctors. (issue #1159)
• Fixed parsing when ParserOptions.AllowUnquotedCommasInAddresses = false. This used to incorrectly allow unquoted commas in address Display Names if the comma followed at least 2 words.

Commits

• d5d4cc9 Bumped version to 4.12.0
• 08a1208 Fixed parsing when ParserOptions.AllowUnquotedCommasInAddresses = false
• c4c5857 protect against multiple Dispose() calls in HtmlWriter
• 4b84acc Added leaveOpen parameters for HtmlWriter .ctors
• 42e37bd Remove old cov-int build data when generating new coverage
• 5fbe474 Anonymize Authentication-Results, DKIM-Signature and ARC headers.
• 23b72dc Use Path.GetRandomFileName() instead of Path.GetTempFileName()
• d7a5b02 Fixed AttachmentCollection to dispose the MimePart if loading content fails
• 9f962e7 Modified AsymmetricAlgorithmExtensions to satisfy static analysis
• f2748cb Get rid of a useless call in GnuPGContext.SignKey()
• Additional commits viewable in compare view

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