Add support for arbitrary indent when w/o `codeIntended`

[tumidi]

Initial checklist

• [x] I read the support docs
• [x] I read the contributing guide
• [x] I agree to follow the code of conduct
• [x] I searched issues and couldn’t find anything (or linked relevant results below)
• [x] If applicable, I’ve added docs and tests

Description of changes

Allows for arbitrary length whitespace prefix on the closing fence line.

[codecov-commenter]

Codecov Report

Merging #3 (02a60e8) into main (c44bc3a) will not change coverage. The diff coverage is 100.00%.

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@@            Coverage Diff            @@
##              main        #3   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          803       805    +2     
=========================================
+ Hits           803       805    +2     

Impacted Files	Coverage Δ
dev/lib/math-flow.js	100.00% <100.00%> (ø)

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[github-actions[bot]]

Hi! This was closed. Team: If this was merged, please describe when this is likely to be released. Otherwise, please add one of the no/* labels.

[wooorm]

Thanks! Released in 2.1.1!