fix(deep-link): handler not set as default on linux

`xdg-mime default` needs to be given the full mimetype, not just the protocol on its own

plugins/deep-link/src/lib.rs

@@ -333,7 +333,7 @@ mod imp {
                     .status()?;
 
                 Command::new("xdg-mime")
-                    .args(["default", &file_name, _protocol.as_ref()])
+                    .args(["default", &file_name, mime_type.as_str()])
                     .status()?;
 
                 Ok(())