fixup!: apply case-insensitive suggestion

Co-authored-by: Michaël Zasso <targos@protonmail.com>

Author: JakobJingleheimer

lib/rules/line-length.js

@@ -35,7 +35,7 @@ export default {
       // Skip lines with URLs.
       if (/https?:\/\//.test(line)) { continue }
       // Skip co-authorship.
-      if (line.startsWith('Co-Authored-By')) { continue }
+      if (/^co-authored-by:/i.test(line)) { continue }
 
       if (line.length > len) {
         failed = true