fix: the text within the <mark> tag didn't parse correctly when pasting HTML

[LucasXu0]

source

now

[codecov]

Codecov Report

Patch coverage: 8.33% and project coverage change: -0.02% ⚠️

Comparison is base (de6801c) 80.59% compared to head (c91b037) 80.58%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #501      +/-   ##
==========================================
- Coverage   80.59%   80.58%   -0.02%     
==========================================
  Files         280      280              
  Lines       11768    11773       +5     
==========================================
+ Hits         9485     9487       +2     
- Misses       2283     2286       +3     

Files Changed	Coverage Δ
...t/image_block_component/image_block_component.dart	56.56% <0.00%> (-1.17%)	⬇️
...mponent/image_block_component/resizable_image.dart	59.03% <0.00%> (-2.22%)	⬇️
lib/src/plugins/html/html_document_decoder.dart	91.71% <100.00%> (+1.18%)	⬆️

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[LucasXu0]

closes #500