The attribute string representation is tailing with a newline now #69
Description
rust-lang/rust#140689 especially rust-lang/rust@e1a177b adds a newline in attributes.
The diff of the affect: d201112#diff-715dddd36ccd9d7762320dee3daa442155492b662edfdeef6d9defcd05ee469eL5-R5
rustdoc-json decides to remove the trailing newline: rust-lang/rust#140762
It doesn't make sense to keep the newline in this tool, either. So we should remove it from each attribute.