fix: escape encoding for titles in rss

quartz/util/escape.ts

@@ -0,0 +1,8 @@
+export const escapeHTML = (unsafe: string) => {
+  return unsafe
+    .replaceAll("&", "&")
+    .replaceAll("<", "&lt;")
+    .replaceAll(">", "&gt;")
+    .replaceAll('"', "&quot;")
+    .replaceAll("'", "&#039;")
+}