Missed escaping a backtick again.

Author: pawchen

.github/workflows/publish_book.yml

@@ -66,7 +66,7 @@ jobs:
             if [ $status -eq 0 ]; then
               rm "$file"
               if [ -n "$msg" ]; then
-                echo "::notice file=$file::Optimized \`$file\` despite \`$msg`"
+                echo "::notice file=$file::Optimized \`$file\` despite \`$msg\`"
               fi
             else
               echo "::warning file=$file::Skipped \`$file\` because \`$msg\`"