Upload GitHub workflow artifacts even when the test fails.

When a test in `.github/workflows/ci.yml`'s `gpu-test` fails,
ensure that it uploads the artifacts anyway. These are screenshots and
comparison images, so they're valuable in debugging the failure.

.github/workflows/ci.yml

@@ -284,6 +284,7 @@ jobs:
           done
 
       - uses: actions/upload-artifact@v3
+        if: always() # We want artifacts even if the tests fail.
         with:
           name: comparison-images
           path: |

tests/src/image.rs

@@ -205,21 +205,18 @@ pub fn compare_image_output(
         }
 
         let file_stem = reference_path.file_stem().unwrap().to_string_lossy();
-        let renderer = format!("{}-{}-{}",
-                               adapter_info.backend.to_str(),
-                               sanitize_for_path(&adapter_info.name),
-                               sanitize_for_path(&adapter_info.driver));
+        let renderer = format!(
+            "{}-{}-{}",
+            adapter_info.backend.to_str(),
+            sanitize_for_path(&adapter_info.name),
+            sanitize_for_path(&adapter_info.driver)
+        );
         // Determine the paths to write out the various intermediate files
         let actual_path = Path::new(&path).with_file_name(
             OsString::from_str(&format!("{}-{}-actual.png", file_stem, renderer)).unwrap(),
         );
         let difference_path = Path::new(&path).with_file_name(
-            OsString::from_str(&format!(
-                "{}-{}-difference.png",
-                file_stem,
-                renderer,
-            ))
-            .unwrap(),
+            OsString::from_str(&format!("{}-{}-difference.png", file_stem, renderer,)).unwrap(),
         );
 
         // Convert the error values to a false color reprensentation
@@ -256,13 +253,7 @@ pub fn compare_image_output(
 
 fn sanitize_for_path(s: &str) -> String {
     s.chars()
-        .map(|ch| {
-            if ch.is_ascii_alphanumeric() {
-                ch
-            } else {
-                '_'
-            }
-        })
+        .map(|ch| if ch.is_ascii_alphanumeric() { ch } else { '_' })
         .collect()
 }