Fix yaml warning
see https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation
the yaml.SafeLoader option seems to be the best choice here.
Quick way to test:
import srim
dbpath = os.path.join(srim.__path__[0], 'data', 'elements.yaml')
a = yaml.load(open(dbpath, "r"), Loader=yaml.SafeLoader)
b = yaml.load(open(dbpath, "r"))
a == b