Minecraft version 1.15, officially titled “The Busy Bee update”, will be released tomorrow, December 10th. Spigot, the developers that provide the server software used on this server, have not yet announced when their 1.15 update will be available.
So until Spigot updates their server software, this server will remain on version 1.14. I’ll update it as soon as Spigot releases a stable, updated version.