Replace deprecated function in Python layer

[hcho3]

No description provided.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.81 ⚠️

Comparison is base (af74664) 85.44% compared to head (22e5b8c) 84.64%.

❗ Current head 22e5b8c differs from pull request most recent head b235c8e. Consider uploading reports for the commit b235c8e to get more accurate results

Additional details and impacted files

@@              Coverage Diff               @@
##             mainline     #487      +/-   ##
==============================================
- Coverage       85.44%   84.64%   -0.81%     
  Complexity         42       42              
==============================================
  Files             111      111              
  Lines            8849     8849              
  Branches           40       40              
==============================================
- Hits             7561     7490      -71     
- Misses           1265     1336      +71     
  Partials           23       23              

Impacted Files	Coverage Δ
python/treelite/frontend.py	77.89% <100.00%> (ø)

... and 12 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.