please explicitly support python 3.13 and 3.14

[e-kwsm]

cffconvert/pyproject.toml

Lines 26 to 27 in b6045d7

	"Programming Language :: Python :: 3.12",
	"Topic :: Scientific/Engineering",

cffconvert/.github/workflows/testing.yml

Line 18 in b6045d7

python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']