feat: change init function to return an error

examples/server_info.rs

@@ -1,7 +1,7 @@
 use libnotify_rs::functions::{self, uninit};
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    functions::init("Morbius");
+    functions::init("Morbius")?;
 
     if let Some(caps) = functions::get_server_caps() {
         println!("=== Server caps ===");

examples/show_notification.rs

@@ -4,7 +4,7 @@ use libnotify_rs::{
 };
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    init("I love coffee");
+    init("I love coffee")?;
     let mut notify = Notification::new(
         "Remember to drink coffe!",
         "Coffee is very important for your mental health!",