feat: use download-artifact instead of manually downloading it

This should hopefully work on private repos too!

.forgejo/workflows/check.yml

@@ -34,8 +34,24 @@ jobs:
           # Create a comment on the associated PR
           comment-on-pr: ${{ github.ref_name != 'main' }}
           # Generate artifacts on main (to speed up comparisons)
-          generate-artifact: ${{ github.ref_name == 'main' }}
+          # generate-artifact: ${{ github.ref_name == 'main' }}
+          # For testing always generate artifacts
+          generate-artifact: 'true'
+          github-token: ${{ secrets.ARTIFACT_TOKEN }}
           # Generate comparisons to main
           do-comparison: 'true'
           # This job's name (so we can find the artifacts)
           job-name: report-size
+  report-download-check:
+    runs-on: nixos
+    needs: report-size
+    steps:
+      - name: Download previous report
+        uses: https://git.salame.cl/actions/download-artifact@d8d0a99033603453ad2255e58720b460a0555e1e # v4
+        with:
+          name: report.json
+          github-token: ${{ secrets.ARTIFACT_TOKEN }}
+          run-id: 15
+      - name: Verify report exists
+        run: |
+          cat report.json