Add a changeset

Author: koddsson

.changeset/red-terms-laugh.md

@@ -0,0 +1,8 @@
+---
+'@web/dev-server-legacy': patch
+'@web/dev-server-rollup': patch
+'rollup-plugin-workbox': patch
+'@web/test-runner-core': patch
+---
+
+Update `browserslist-useragent`