Security & Format update

[Vinfall]

• Bump dependencies, most importantly request to address a security issue, see https://github.com/Vinfall/SteamWishlistCalendar/security/dependabot/1 and Use TLS settings in selecting connection pool psf/requests#6655
• Update ics package to comply with the new RFC 5545 which obsoletes RFC 2445 (which ics 0.7.2 used), see Vinfall/VNDB-Calendar@d9e36db. The generated iCalendar is a bit different but still backward-compatible. With this, SteamWishlistCalendar should now work in more clients.

[icue]

Thanks a lot!