nano: update to 5.8

2021.06.15 - GNU nano 5.8 "Why is it necessary to be special?"
• After a search, the spotlighting is dropped after 1.5 seconds (0.8
  seconds with --quick) to avoid the idea that the text is selected.
• A + and a space before a filename on the command line will put the
  cursor at the end of the corresponding buffer.
• Linter messages no longer include filename and line/column numbers.
• Color name "grey" or "gray" can be used instead of "lightblack".
• The color of the minibar can be chosen with 'set minicolor'.


(nia)