fix: parse keyframes percentage selectors

[bartveneman]

closes #130

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.97%. Comparing base (e2b2aba) to head (aa11593).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #131   +/-   ##
=======================================
  Coverage   94.96%   94.97%           
=======================================
  Files          16       16           
  Lines        2623     2625    +2     
  Branches      681      682    +1     
=======================================
+ Hits         2491     2493    +2     
  Misses        132      132           

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[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 114 bytes (0.08%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@projectwallace/css-parser-esm	142.08kB	114 bytes (0.08%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: @projectwallace/css-parser-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
parse-*.js	114 bytes	26.19kB	0.44%

Files in parse-*.js:

• ./src/parse-selector.ts → Total Size: 24.8kB