Add rule to prevent co-author line length violations (#484)

Signed-off-by: Matty Widdop <18513864+MattyTheHacker@users.noreply.github.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: MattyTheHacker

.gitlint

@@ -11,5 +11,8 @@ ignore = T1,B1,B5,B6
 regex = \AMerge\s+[a-f0-9]{8,64}\s+into\s+[a-f0-9]{8,64}\Z
 ignore = T1,B5,B6
 
+[ignore-body-lines]
+regex = (?i)^Co-Authored-By
+
 [title-must-not-contain-word]
 words = fuck,stupid,annoying,rubbish,shit,crap