Fixed implicit cast in shadowpass.

ScriptableRenderPipeline/LightweightPipeline/LWRP/ShaderLibrary/LightweightPassShadow.hlsl

 {
     LightweightVertexOutput o = LitPassVertex(v);
 
-    float invNdotL = 1.0 - saturate(dot(_LightDirection, o.normal));
+    float invNdotL = 1.0 - saturate(dot(_LightDirection, o.normal.xyz));
-    o.posWSShininess.xyz = o.normal * scale.xxx + o.posWSShininess.xyz;
+    o.posWSShininess.xyz = o.normal.xyz * scale.xxx + o.posWSShininess.xyz;
     float4 clipPos = TransformWorldToHClip(o.posWSShininess.xyz);
 
     // _ShadowBias.x sign depens on if platform has reversed z buffer