fix(stepper,infieldbutton,picker): s2 foundations fast follows

- create changeset

Author: marissahuysentruyt

.changeset/nervous-penguins-matter.md

@@ -0,0 +1,11 @@
+---
+"@spectrum-css/infieldbutton": patch
+"@spectrum-css/stepper": patch
+"@spectrum-css/picker": patch
+---
+
+S2 Foundations fixes
+
+- Adjusts the background-color of the infield button components within stepper to use `gray-100` as opposed to `gray-25`.
+  - This corresponds to the updates picker has for S2.
+- Corrects the border color for the default picker for S2 foundations, using `gray-500` (instead of `gray-800`) to align with other field/form components.