Fix missing `!void` in std.MultiArrayList
Fix missing `!void` in std.MultiArrayList

Calling `insert` on a `std.MultiArrayList` currently fails with a compiler error due to using a `try` without the `!` annotation on the return type

```zig
this.list.insert(allocator, 0, listener);
```

```zig
/Users/jarred/Build/zig/lib/std/multi_array_list.zig:192:13: error: expected type 'void', found '@typeInfo(@typeInfo(@TypeOf(std.multi_array_list.MultiArrayList(src.javascript.jsc.node.types.Listener).ensureUnusedCapacity)).Fn.return_type.?).ErrorUnion.error_set'
            try self.ensureUnusedCapacity(gpa, 1);
```
andrewrk/zig,andrewrk/zig