CompatHelper: bump compat for DocStringExtensions to 0.9, (keep existing compat)

[github-actions[bot]]

This pull request changes the compat entry for the DocStringExtensions package from 0.8 to 0.8, 0.9. This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov-commenter]

Codecov Report

Merging #39 (d3e3ccd) into main (7256412) will decrease coverage by 0.23%. The diff coverage is n/a.

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
- Coverage   98.65%   98.42%   -0.24%     
==========================================
  Files           4        4              
  Lines         671      636      -35     
==========================================
- Hits          662      626      -36     
- Misses          9       10       +1     

Impacted Files	Coverage Δ
src/KiteModels.jl	97.33% <0.00%> (-0.72%)	:arrow_down:
src/KPS3.jl	97.91% <0.00%> (-0.12%)	:arrow_down:
src/KPS4.jl	99.06% <0.00%> (-0.06%)	:arrow_down:
src/init.jl	100.00% <0.00%> (ø)

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[ufechner7]

Added to Project.toml