fix: solves issue, that opacity is reset at iteration 0 (#735)

Author: kleinicke

gsplat/strategy/default.py

@@ -192,7 +192,7 @@ def step_post_backward(
                 state["radii"].zero_()
             torch.cuda.empty_cache()
 
-        if step % self.reset_every == 0:
+        if step % self.reset_every == 0 & step > 0:
             reset_opa(
                 params=params,
                 optimizers=optimizers,