Fix bug with case-insensitive filesystems

- Path exists conflict is no longer triggered when the casing of a
  filename is changed. e.g from abc.md to ABC.md

src/replace.go

@@ -383,7 +383,7 @@ func getAllVariables(str string) (replaceVars, error) {
 	return v, nil
 }
 
-// regexReplace handles string replacement in regex mode
+// regexReplace handles string replacement
 func (op *Operation) regexReplace(
 	r *regexp.Regexp,
 	fileName, replacement string,

src/validation.go

@@ -200,7 +200,8 @@ func (op *Operation) detectConflicts() {
 		if _, err := os.Stat(target); err == nil ||
 			errors.Is(err, os.ErrExist) {
 			// Don't report a conflict for an unchanged filename
-			if source == target {
+			// Also handles case-insensitive filesystems
+			if strings.EqualFold(source, target) {
 				continue
 			}