Update kitty temp file naming (#51)

Kitty does not consistently remove tmp files on all operating systems. Whenever it is unsure if the directory is a temporary directory, kitty will leave the image for security reasons. This will lead to eventually running out of tmp files and viuer no longer working. By changing the name to include `tty-graphics-protocol`, kitty will always delete the tmp file.

src/printer/kitty.rs

@@ -8,7 +8,7 @@ use std::io::{Error, ErrorKind};
 
 pub struct KittyPrinter;
 
-const TEMP_FILE_PREFIX: &str = ".tmp.viuer.";
+const TEMP_FILE_PREFIX: &str = ".tty-graphics-protocol.viuer.";
 lazy_static! {
     static ref KITTY_SUPPORT: KittySupport = check_kitty_support();
 }