[MacPorts] #68039: difftastic: update port to 0.51

[MacPorts]

#68039: difftastic: update port to 0.51
--------------------+-------------------------
 Reporter:  sierkb  |      Owner:  herbygillot
     Type:  update  |     Status:  assigned
 Priority:  Normal  |  Milestone:
Component:  ports   |    Version:  2.8.1
 Keywords:          |       Port:  difftastic
--------------------+-------------------------
 Please update the difftastic port to the latest upstream version, which is
 0.51 as of
 https://github.com/Wilfred/difftastic/releases resp.
 https://github.com/Wilfred/difftastic/blob/master/CHANGELOG.md

-- 
Ticket URL: <https://trac.macports.org/ticket/68039>
MacPorts <https://www.macports.org/>
Ports system for macOS