chore(deps): update dependency mailkit to 4.9.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
MailKit (source)	4.6.0 -> 4.9.0

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Release Notes

jstedfast/MailKit (MailKit)

v4.9.0

Compare Source

• Added an IMAP work-around for mail.ru which sometimes sends integer tokens as decimals in its responses.
  (issue #​1838)
• Added a workaround for GMail IMAP BODY responses that include multipart expressions without any children
  (e.g. ("ALTERNATIVE")). (issue #​1841)
• Fixed default system proxy to handle null credentials and check if the targetUri is bypassed.
  (issue #​1852)
• Dropped support for net6.0 (Microsoft support ended Nov 12, 2024).
• Bumped System.Threading.Tasks.Extensions dependency to 4.6.0.
• Bumped MimeKit dependency to 4.9.0.

v4.8.0

Compare Source

• Added a UniqueIdRange.SortOrder property.
• Updated the protocol log help link for ProtocolExceptions.
  (issue #​1800)
• Fix SmtpClient.Dispose() when telemetry is configured.
  (issue #​1816)
• Added ProxyClient.SystemProxy as a convenience property that wraps
  the default system proxy (aka HttpClient.DefaultProxy) on net6.0+.

v4.7.1.1

Compare Source

v4.7.1

Compare Source

• Fixed ImapClient and Pop3Client.Connect/Async() when OTEL is enabled.
  (issue #​1765)
• Bumped MimeKit dependency to 4.7.1 to fix a denial of service security issue in the System.Formats.Asn1
  dependency.

v4.7.0

Compare Source

• Added Activity/Metrics for Imap/Pop3/SmtpClient.
  (issue #​1499)
• Bumped MimeKit dependency to 4.7.0.

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