CI: Update scientific-python/upload-nightly-action to 0.2.0

* The scientific-python/upload-nightly-action action has received
  stability updates in 0.2.0 that provides a reproducible runtime
  environment for the action, which should mitigate issues with
  stability.
   - c.f. https://github.com/scientific-python/upload-nightly-action/releases/tag/0.2.0

Author: matthewfeickert

.github/workflows/nightlies.yml

@@ -59,7 +59,7 @@ jobs:
           ls -l dist/
 
       - name: Upload wheels to Anaconda Cloud as nightlies
-        uses: scientific-python/upload-nightly-action@8f0394fd2aa0c85d7364a9958652e8994e06b23c # 0.1.0
+        uses: scientific-python/upload-nightly-action@5fb764c5bce1ac2297084c0f7161b1919f17c74f # 0.2.0
         with:
           artifacts_path: dist
           anaconda_nightly_upload_token: ${{ secrets.ANACONDA_ORG_UPLOAD_TOKEN }}