escape backticks

Author: pawchen

.github/workflows/publish_book.yml

@@ -47,10 +47,10 @@ jobs:
             if [ $status -eq 0 ]; then
               rm "$file"
               if [ -n "$msg" ]; then
-                echo "::notice file=$file::Optimized `$file` but `$msg`"
+                echo "::notice file=$file::Optimized \`$file\` but \`$msg\`"
               fi
             else
-              echo "::warning file=$file::Skipped `$file` because `$msg`"
+              echo "::warning file=$file::Skipped \`$file\` because \`$msg\`"
             fi'
 
       - name: Optimize gif images
@@ -66,10 +66,10 @@ jobs:
             if [ $status -eq 0 ]; then
               rm "$file"
               if [ -n "$msg" ]; then
-                echo "::notice file=$file::Optimized `$file` but `$msg`"
+                echo "::notice file=$file::Optimized \`$file` but \`$msg`"
               fi
             else
-              echo "::warning file=$file::Skipped `$file` because `$msg`"
+              echo "::warning file=$file::Skipped \`$file\` because \`$msg\`"
             fi'
 
       - name: Optimize text