Fixes issue with multiline collections formatting. (FuelLabs#3158)

Fixes issue FuelLabs#3014.

The following code ...
```
let x = (
    "hello",
    "world",
);
```
... was formatted into:
```
let x = ("hello", "world", );
```
After the fix it is formatted into:
```
let x = ("hello", "world");
```

Co-authored-by: Joshua Batty <[email protected]>
Co-authored-by: Kaya Gökalp <[email protected]>

swayfmt/src/formatter/mod.rs

@@ -1124,6 +1124,28 @@ fn struct_destructuring() {
         nested_tuple: (a, (b, (c, d))),
     } = tuple_in_struct;
 }
+"#;
+        let mut formatter = Formatter::default();
+        let formatted_sway_code =
+            Formatter::format(&mut formatter, Arc::from(sway_code_to_format), None).unwrap();
+        assert_eq!(correct_sway_code, formatted_sway_code);
+        assert!(test_stability(formatted_sway_code, formatter));
+    }
+
+    #[test]
+    fn test_multiline_collections() {
+        let sway_code_to_format = r#"library test_multiline_collections;
+fn func_with_multiline_collections() {
+    let x = (
+        "hello",
+        "world",
+    );
+}
+"#;
+        let correct_sway_code = r#"library test_multiline_collections;
+fn func_with_multiline_collections() {
+    let x = ("hello", "world");
+}
 "#;
         let mut formatter = Formatter::default();
         let formatted_sway_code =

swayfmt/src/utils/language/punctuated.rs

@@ -31,6 +31,9 @@ where
 
                     if let Some(final_value) = &self.final_value_opt {
                         final_value.format(formatted_code, formatter)?;
+                    } else {
+                        formatted_code.pop();
+                        formatted_code.pop();
                     }
                 }
                 LineStyle::Inline => {