fix: show swallowed exceptions and handle empty MIME header values (#36)

* fix: swallowed exceptions and handle empty MIME header values

* fix: filter out headers wth null/empty values

Co-authored-by: queil <queil@users.noreply.github.com>

updated dependencies

bumping version

Updating to MimeKit 2.5.1 and bumping version

Bumped version to 2.0.0.6, updated sourcelink & fixed issue with publish

fixed azure build pipelines