fix: try python executable first

[frostming]

Pull Request Check List

• A news fragment is added in news/ describing what is new.
• Test cases added for changed code.

Describe what you have changed in this PR.

Fix #1255

[codecov-commenter]

Codecov Report

Merging #1260 (f7fd6e9) into main (2ef53aa) will increase coverage by 0.18%.
The diff coverage is 74.19%.

@@            Coverage Diff             @@
##             main    #1260      +/-   ##
==========================================
+ Coverage   81.33%   81.52%   +0.18%     
==========================================
  Files          93       93              
  Lines        7647     7642       -5     
  Branches     1786     1808      +22     
==========================================
+ Hits         6220     6230      +10     
+ Misses       1066     1053      -13     
+ Partials      361      359       -2     

Flag	Coverage Δ
unittests	81.40% <74.19%> (+0.17%)	⬆️

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Impacted Files	Coverage Δ
pdm/project/core.py	89.78% <74.19%> (+0.35%)	⬆️
pdm/utils.py	82.88% <0.00%> (+4.94%)	⬆️

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