Add wheels CI badge to README
[![Quick CI Tests](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/on_push_tests.yml/badge.svg)](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/on_push_tests.yml)
[![Daily CI Tests](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/daily_tests.yml/badge.svg)](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/daily_tests.yml)
[![Documentation](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/docs_test.yml/badge.svg)](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/docs_test.yml)
+[![Wheels](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/wheels.yml/badge.svg?event=schedule)](https://github.com/siliconcompiler/siliconcompiler/actions/workflows/wheels.yml)
SiliconCompiler ("SC") is a open source compiler infrastructure project that aims
to lower the barrier to hardware specialization through a simple distributed
