change github action ubuntu version 18.04 -> latest

[injae]

Description

• fix github action Waiting for a runner to pick up this job...

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (3098c86) 68.53% compared to head (70dc991) 64.25%.
Report is 23 commits behind head on main.

Files	Patch %	Lines
include/serdepp/serializer.hpp	20.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #60      +/-   ##
==========================================
- Coverage   68.53%   64.25%   -4.28%     
==========================================
  Files          16       16              
  Lines         518      540      +22     
  Branches        0       70      +70     
==========================================
- Hits          355      347       -8     
+ Misses        163      155       -8     
- Partials        0       38      +38     

Flag	Coverage Δ
unittest	?

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.