fix(RadioButtonGroup): add focus state (#1541)

## 📝 Changes

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made.

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developers reviewing this pull request.

## ✅ Checklist

Easy UI has certain UX standards that must be met. In general,
non-trivial changes should meet the following criteria:

- [x] Visuals match Design Specs in Figma
~- [ ] Stories accompany any component changes~
- [x] Code is in accordance with our style guide
- [x] Design tokens are utilized
~- [ ] Unit tests accompany any component changes~
~- [ ] TSDoc is written for any API surface area~
~- [ ] Specs are up-to-date~
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~- [ ] No accessibility violations are reported~
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.changeset/polite-hounds-mate.md

@@ -0,0 +1,5 @@
+---
+"@easypost/easy-ui": patch
+---
+
+fix(RadioButtonGroup): add focus state

easy-ui-react/src/RadioButtonGroup/RadioButtonGroup.module.scss

@@ -45,4 +45,9 @@
     color: design-token("color.neutral.600");
     border-color: design-token("color.neutral.300");
   }
+
+  &[data-focus-visible] {
+    z-index: 3;
+    box-shadow: design-token("shadow.button");
+  }
 }