change CircularProgressIndicator to be adaptive

[binSaed]

chewie/lib/src/cupertino/cupertino_controls.dart

Line 98 in b847af3

child: CircularProgressIndicator(),

To

CircularProgressIndicator.adaptive()

[diegotori]

@abdoosaed I do take pull requests for this change. Please submit one at your earliest convenience and I'll be glad to review it.