Use stack based allocator

src/main.zig

@@ -70,7 +70,13 @@ pub fn main() !void {
         _ = d.deinit();
     };
 
-    var allocator = if (dba) |*d| d.allocator() else std.heap.smp_allocator;
+    var allocator = if (dba) |*d|
+        d.allocator()
+    else blk: {
+        var buf: [128]u8 = undefined;
+        var fba = std.heap.FixedBufferAllocator.init(&buf);
+        break :blk fba.allocator();
+    };
 
     const msg = SaprusMessage{
         .relay = .{