Bumped version to 1.1.0

Updated `@since` annotations and Gradle version to match the release.

Author: NonSwag

api/src/main/java/net/thenextlvl/perworlds/WorldGroup.java

@@ -381,7 +381,7 @@ default boolean isLoadingData(Player player) {
      * @param player the offline player whose data is to be persisted and modified
      * @param data   a {@link Consumer} that manipulates the {@link PlayerData} object
      * @see #persistPlayerData(Player, Consumer)
-     * @since 1.0.3
+     * @since 1.1.0
      */
     @Contract(mutates = "io")
     void persistPlayerData(OfflinePlayer player, Consumer<PlayerData> data);