Add missing `Ahrefs` regex to bots list

[summercms]

There are missing Ahrefs bots and so this pr will update the Ahrefs regex.

Ahrefs Bot

New UA (latest):

Mozilla/5.0 (compatible; AhrefsBot/7.0; +http://ahrefs.com/robot/)

New UA (current):

Mozilla/5.0 (compatible; AhrefsBot/6.1; http://ahrefs.com/robot/)

Mozilla/5.0 (compatible; AhrefsBot/6.1; +http://ahrefs.com/robot/)

Old UA:

Mozilla/5.0 (compatible; AhrefsBot/5.2; +http://ahrefs.com/robot/)

Mozilla/5.0 (compatible; AhrefsBot/5.2; http://ahrefs.com/robot/)

Mozilla/5.0 (compatible; AhrefsBot/2.0; +http://ahrefs.com/robot/)

Ahrefs News Bot

New UA:

Mozilla/5.0 (compatible; AhrefsBot/7.0; News; +http://ahrefs.com/robot/)

Mozilla/5.0 (compatible; AhrefsBot/6.1; News; +http://ahrefs.com/robot/)

Old UA:

Mozilla/5.0 (compatible; AhrefsBot/5.2; News; +http://ahrefs.com/robot/)

Ahrefs SA Bot

Mozilla/5.0 (compatible; AhrefsBot/7.0; SA; +http://ahrefs.com/robot/)

Mozilla/5.0 (compatible; AhrefsBot/6.1; SA; +http://ahrefs.com/robot/)

Ahrefs Site Audit Bot

Mozilla/5.0 (compatible; AhrefsSiteAudit/6.1; +http://ahrefs.com/robot/)

Ahrefs Feeds Bot

AhrefsBot.Feeds v0.1; http://ahrefs.com/

Reverse DNS

ip-54-36-148-103.a.ahrefs.com

Dead Bots

Ahrefs Bot (2011 - 2017)

Mozilla/5.0 (compatible; AhrefsBot/5.1; +http://ahrefs.com/robot/)
Mozilla/5.0 (compatible; AhrefsBot/5.0; +http://ahrefs.com/robot/)
Mozilla/5.0 (compatible; AhrefsBot/4.0; +http://ahrefs.com/robot/)
Mozilla/5.0 (compatible; AhrefsBot/3.1; +http://ahrefs.com/robot/)
Mozilla/5.0 (compatible; AhrefsBot/3.0; +http://ahrefs.com/robot/)
Mozilla/5.0 (compatible; AhrefsBot/1.0; +http://ahrefs.com/robot/)

Link: https://ahrefs.com/robot

Link: https://ahrefs.com/

[coveralls]

Coverage increased (+0.02%) to 99.97% when pulling 1046dd947abed41f16bf390ae6f3dc9d5dd26bc8 on ayumi-cloud:ahrefs into 880b9fa797401d14b28956442944c3daa70240ff on WhichBrowser:master.

[NielsLeenheer]

Fixed in 63730e53d0e328787dbcbb96f1bae0a3370713a8