[master] Bump swiftmailer/swiftmailer from 5.4.8 to 6.0.2

[dependabot-preview]

Bumps swiftmailer/swiftmailer from 5.4.8 to 6.0.2.

• Changelog
• Commits

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

If you'd like to skip this version, you can just close this PR. If you have any feedback just mention @dependabot in the comments below.

[dependabot-preview]

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.

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

[DeepDiver1975]

@dependabot ignore this major version

[dependabot-preview]

OK, I won't notify you about version 6.x.x again, unless you re-open this PR or update to a 6.x.x release yourself.

[codecov]

Codecov Report

Merging #29943 into master will decrease coverage by <.01%.
The diff coverage is 75%.

@@             Coverage Diff              @@
##             master   #29943      +/-   ##
============================================
- Coverage     64.12%   64.12%   -0.01%     
+ Complexity    18720    18716       -4     
============================================
  Files          1184     1184              
  Lines         70437    70429       -8     
  Branches       1270     1270              
============================================
- Hits          45171    45165       -6     
+ Misses        24896    24894       -2     
  Partials        370      370

Flag	Coverage Δ	Complexity Δ
#javascript	52.89% <ø> (ø)	0 <ø> (ø)	⬇️
#phpunit	65.4% <75%> (-0.01%)	18716 <0> (-4)

Impacted Files	Coverage Δ	Complexity Δ
lib/private/Mail/Mailer.php	76.71% <75%> (+0.16%)	22 <0> (-4)	⬇️

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[VicDeo]

@DeepDiver1975 tested in SMTP mode, works.
Please consider removal of unused import