Add empty test to main

src/main.zig

@@ -14,6 +14,10 @@ pub fn main() anyerror!void {
     return sys.runGraphics(anyerror, run);
 }
 
+test {
+    // Empty test is here to run all others (for now).
+}
+
 fn run(event_loop: *sys.EventLoop, graphics: *sys.GraphicsContext) anyerror!void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};