make trailing-spaces ignore YAML to avoid conflict with insert-yaml-attributes

[chrisgrieser]

Right now, the attributes added by insert-yaml-attributes are missing trailing spaces, even when they they are set in the settings. so when I have tags: there, then after linting, I only get tags: in my document. I assume this is due to the trailing-spaces rule not ignoring yaml.

Having that trailing whitespace there is actually useful, since you need a space after the : in yaml to have valid yaml, having the space there saves the time of manually typing it every time.