Add flex-shrink to IconButton + tests (#5467)

* add flex-shrink

* Create short-fireants-jog.md

* fix test

* try rename

* fix regression

* fine

* fix test

* test(e2e): update ActionBar test

* test(vrt): update snapshots

---------

Co-authored-by: Josh Black <[email protected]>
Co-authored-by: langermank <[email protected]>

Author: langermank

.changeset/short-fireants-jog.md

@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+Add `flex-shrink` to IconButton