Update edition to 2024

And remove unstable let_chains feature which isn't needed anymore.

Signed-off-by: pep <pep@bouah.net>

src/main.rs

@@ -13,8 +13,6 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
-#![feature(let_chains)]
-
 mod bot;
 mod config;
 mod error;