Feat: Increment version to 0.3.21

- Iterated the patch version for the iCalendar plug from 0.3.20 to 0.3.21.
- Updated  and  with the new version.
- This change is intended to be built and deployed via Gitea Actions.

icalendar.ts

@@ -1,7 +1,7 @@
 import { clientStore, config, datastore, editor, index } from "@silverbulletmd/silverbullet/syscalls";
 import { convertIcsCalendar } from "https://esm.sh/ts-ics@2.4.0";
 
-const VERSION = "0.3.20";
+const VERSION = "0.3.21";
 const CACHE_KEY = "icalendar:lastSync";
 
 console.log(`[iCalendar] Plug script executing at top level (Version ${VERSION})`);