Fix Windows failures

Author: lionel-

crates/ark_test/src/dummy_frontend.rs

@@ -451,7 +451,7 @@ impl DummyArkFrontend {
         write!(file, "{code}").unwrap();
 
         let url = ExtUrl::from_file_path(file.path()).unwrap();
-        let path = url.path().to_string();
+        let path = url.to_file_path().unwrap().to_string_lossy().to_string();
         let uri = url.to_string();
         let filename = file
             .path()
@@ -667,7 +667,7 @@ impl SourceFile {
         write!(file, "{code}").unwrap();
 
         let url = ExtUrl::from_file_path(file.path()).unwrap();
-        let path = url.path().to_string();
+        let path = url.to_file_path().unwrap().to_string_lossy().to_string();
         let uri = url.to_string();
 
         // Extract file name