Fix unsupported data dtype for FindContours in vista2d (#678)

Fixes #677

### Description
Use `cv2.convertScaleAbs` function to scale and convert the label to an
8-bit format then apply find_contours, it will not influence the result
of the contours.

### Status
**Ready/Work in progress/Hold**

### Please ensure all the checkboxes:
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Codeformat tests passed locally by running `./runtests.sh
--codeformat`.
- [ ] In-line docstrings updated.
- [ ] Update `version` and `changelog` in `metadata.json` if changing an
existing bundle.
- [ ] Please ensure the naming rules in config files meet our
requirements (please refer to: `CONTRIBUTING.md`).
- [ ] Ensure versions of packages such as `monai`, `pytorch` and `numpy`
are correct in `metadata.json`.
- [ ] Descriptions should be consistent with the content, such as
`eval_metrics` of the provided weights and TorchScript modules.
- [ ] Files larger than 25MB are excluded and replaced by providing
download links in `large_file.yml`.
- [ ] Avoid using path that contains personal information within config
files (such as use `/home/your_name/` for `"bundle_root"`).

---------

Signed-off-by: YunLiu <[email protected]>
Co-authored-by: Yiheng Wang <[email protected]>

models/vista2d/configs/metadata.json

@@ -1,7 +1,8 @@
 {
     "schema": "https://github.com/Project-MONAI/MONAI-extra-test-data/releases/download/0.8.1/meta_schema_20240725.json",
-    "version": "0.2.8",
+    "version": "0.2.9",
     "changelog": {
+        "0.2.9": "fix unsupported data dtype in findContours",
         "0.2.8": "remove relative path in readme",
         "0.2.7": "enhance readme",
         "0.2.6": "update tensorrt benchmark results",

models/vista2d/scripts/components.py

@@ -251,6 +251,7 @@ def __call__(self, data):
                 cv2.imwrite(output_filepath, image)
                 logger.info(f"Overlay Masks: Saving {output_filepath}")
             else:
+                label = cv2.convertScaleAbs(label, alpha=255.0 / label.max())
                 contours, _ = cv2.findContours(label, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)
                 polygons.extend(self.to_polygons(contours))