v6.1.0

Added

• omit sourcesContent if all of the values are null (#287)

Fixed

• encode sourcesContent null as raw null instead of quoted string (#291)

Other

• avoid temporary Vec in ConcatSourceMapBuilder::add_sourcemap (#290)
• combine source_contents scans in encode_to_string (#289)
• avoid double Arc allocation in add_source_and_content (#288)
• apply cargo shear --fix (#285)