Fixed issue in test framework that was incorrectly blending alpha. Fixed issue in specular of simple lighting shader.

ScriptableRenderPipeline/LightweightPipeline/Shaders/LightweightPassLit.cginc

     half fogFactor = IN.fogFactorAndVertexLight.x;
 
 #if defined(_SPECGLOSSMAP) || defined(_SPECULAR_COLOR)
-    half4 specularGloss = SpecularGloss(uv, alpha);
+    half4 specularGloss = SpecularGloss(uv, diffuseAlpha.a);
     return LightweightFragmentBlinnPhong(positionWS, normalWS, viewDirectionWS, fogFactor, diffuseGI, diffuse, specularGloss, shininess, emission, alpha);
 #else
     return LightweightFragmentLambert(positionWS, normalWS, viewDirectionWS, fogFactor, diffuseGI, diffuse, emission, alpha);

Tests/GraphicsTests/Framework/Editor/TestFramework.cs

 			// Readback the rendered texture
 			var oldActive = RenderTexture.active;
 			RenderTexture.active = tempTarget;
-			var captured = new Texture2D(tempTarget.width, tempTarget.height, TextureFormat.ARGB32, false);
+			var captured = new Texture2D(tempTarget.width, tempTarget.height, TextureFormat.RGB24, false);
 			captured.ReadPixels(new Rect(0, 0, testSetup.width, testSetup.height), 0, 0);
 			RenderTexture.active = oldActive;