There is no stable version that is py37 compatible. Please also check all other packages you maintain that depend on python.
Sanity check failed: > dev-util/vint-0.3.21 > bdepend amd64 stable profile default/linux/amd64/17.0 (28 total) > >=dev-python/ansicolor-0.2.4[-python_single_target_python3_6(-),-python_single_target_python3_7(-),-python_single_target_python3_8(-),python_targets_python3_6(-),python_targets_python3_7(-)] > bdepend amd64 dev profile default/linux/amd64/17.0/no-multilib/prefix/kernel-3.2+ (2 total) > >=dev-python/ansicolor-0.2.4[-python_single_target_python3_6(-),-python_single_target_python3_7(-),-python_single_target_python3_8(-),python_targets_python3_6(-),python_targets_python3_7(-)] > rdepend amd64 stable profile default/linux/amd64/17.0 (28 total) > >=dev-python/ansicolor-0.2.4[-python_single_target_python3_6(-),-python_single_target_python3_7(-),-python_single_target_python3_8(-),python_targets_python3_6(-),python_targets_python3_7(-)] > rdepend amd64 dev profile default/linux/amd64/17.0/no-multilib/prefix/kernel-3.2+ (2 total) > >=dev-python/ansicolor-0.2.4[-python_single_target_python3_6(-),-python_single_target_python3_7(-),-python_single_target_python3_8(-),python_targets_python3_6(-),python_targets_python3_7(-)]
All sanity-check issues have been resolved