[Bug]: sp-action-group change event fires before selection change

### Code of conduct

- [x] I agree to follow this project's code of conduct.

### Impacted component(s)

sp-action-group

### Expected behavior

When using a sp-action-group acts as a radio group with the selects="single" attribute, the change event should dispatch after the sp-action-button child is assigned a selected attribute.

### Actual behavior

The change event dispatches before the sp-action-button is given the selected attribute so the changed state is still the previous value.

### Screenshots

_No response_

### What browsers are you seeing the problem in?

_No response_

### How can we reproduce this issue?

see sample code

### Sample code or abstract reproduction which illustrates the problem

```

One
Two
Three

```

```
onChange(){
const rotation = this.renderRoot.querySelector("#rotation sp-action-button[selected]")?.getAttribute("value");

if (rotation){
console.log(rotation);
}
}
```

### Severity

SEV 3

### Logs taken while reproducing problem

_No response_

Start by locating the sp-action-group implementation and reproduce the sample with selects="single" and the change handler shown. Verify that the child sp-action-button has its selected attribute updated before the change event runs, and confirm the handler reads the newly selected value.

Written by the indexing model from the issue text.