Use ISO8601 timestamps for the CalDAV trashbin

[ChristophWurst]

• Requires Use ISO8601 timestamps for the CalDAV trashbin server#27632
• Requires Use ISO8601 timestamps for the CalDAV trashbin cdav-library#503 but will also be flexible enough to work without

[codecov]

Codecov Report

Merging #3251 (233c577) into master (de512e6) will decrease coverage by 0.02%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master    #3251      +/-   ##
============================================
- Coverage     28.89%   28.87%   -0.03%     
  Complexity      122      122              
============================================
  Files           157      157              
  Lines          5735     5739       +4     
  Branches        843      844       +1     
============================================
  Hits           1657     1657              
- Misses         4078     4082       +4     

Flag	Coverage Δ
javascript	23.37% <0.00%> (-0.02%)	⬇️
php	94.58% <ø> (ø)

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Impacted Files	Coverage Δ
...c/components/AppNavigation/CalendarList/Moment.vue	0.00% <0.00%> (ø)

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