Update release task to use nested build-files assets

Author: tyeth

.github/workflows/release-callee.yml

@@ -22,6 +22,6 @@ jobs:
         if: startsWith(github.ref, 'refs/tags/')
         with:
           files: |
-                  wippersnapper.*.uf2
-                  wippersnapper.*.bin
-                  wippersnapper.*.zip
+                  build-files/wippersnapper.*.uf2
+                  build-files/wippersnapper.*.bin
+                  build-files/wippersnapper.*.zip