fix: zola panic if no static dir

[amtanq]

Fixes: #2604

Root Cause:

• Application panicked at this code std::fs::canonicalize(&output_path).unwrap() when there is no static directory and compile_sass is set to false
• Reason for this is output_path (which in default case is public) does not get created
  • Folder gets created when there is a static folder or we have compile_sass set
• Added create_directory code to create the directory if it does not exist before canonicalize

Alternate fix

Handle unwrap and show an error

[Keats]

Not entirely sure why it's causing an issue because of the static folder but lgtm