chore: bump miniflare to 3.20230821.0

Author: mrbbot

.changeset/spicy-cherries-happen.md

@@ -0,0 +1,6 @@
+---
+"@cloudflare/pages-shared": minor
+"wrangler": minor
+---
+
+chore: bump `miniflare` to [`3.20230821.0`](https://github.com/cloudflare/miniflare/releases/tag/v3.20230821.0)

fixtures/pages-ws-app/package.json

@@ -16,7 +16,7 @@
 	},
 	"devDependencies": {
 		"@cloudflare/workers-tsconfig": "*",
-		"miniflare": "3.20230814.1",
+		"miniflare": "3.20230821.0",
 		"wrangler": "*",
 		"ws": "^8.8.0"
 	},