office-ui-fabric-react v7.111.0

Minor changes

• Add custom expand icon support to Group Header (PR #13011 by bcoard)

Patches

• update snapshots for merge-styles change to not generate class with no styles (PR #13029 by pingj)
• Prettier fix on Callout test. (PR #12339 by khmakoto)
• Checkbox: fix high contrast styles in Edge Chromium (PR #13035 by xugao)
• Cleaning up callout, announced, and calendar examples (PR #13053 by czearing)