Salmon 1.5.2

This is a minor release and introduced no new features. However, this release addresses the issue raised in #688. Specifically, when run in RAD mode (i.e. with --rad or --sketch), salmon alevin did not output a cmd_info.json or meta_info.json file. While not strictly required for subsequent processing with alevin-fry, having this information can be useful for provenance tracking and bookkeeping. Now, both of these files are properly generated when running salmon alevin in RAD mode.