Log Message:
sysutils/bkt: update to 0.7.0

What's Changed
 - stdout/stderr are now streamed as the subprocess is executing, rather than
   output only once the subprocess completes (#43).
 - NotFound errors during cleanup are now ignored (#42).
 - Improved error handling for malformed executables (#37).

API Changes
 - New methods Bkt::retrieve_streaming and Bkt::refresh_streaming have been
   added for library users that want to stream output, however these methods
   are subject to change and should be treated as experimental.