[3.10] replace `self` param with more appropriate `cls` in classmethods (GH-31402) (GH-31446)

(cherry picked from commit a3fcca4af1cb418dc802feb75100ecc1a286afaa)

Co-authored-by: Josh Smith <cmyuiosu@gmail.com>

Co-authored-by: Josh Smith <cmyuiosu@gmail.com>
1 file changed