chore: 📦 add jsdom

Author: spences10

package.json

@@ -62,6 +62,7 @@
 		"eslint-config-prettier": "^8.7.0",
 		"eslint-plugin-svelte3": "^4.0.0",
 		"fathom-client": "^3.5.0",
+		"jsdom": "^21.1.1",
 		"mdsvex": "^0.10.6",
 		"postcss": "^8.4.14",
 		"postcss-load-config": "^4.0.1",