tests: Mark some tests as requiring shader model 4.0.

Signed-off-by: Zebediah Figura <zfigura@codeweavers.com>
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

tests/cast-to-float.shader_test

@@ -1,5 +1,7 @@
-[pixel shader]
+[require]
+shader model >= 4.0
 
+[pixel shader]
 float4 main(uniform int i, uniform uint u, uniform bool b, uniform half h) : sv_target
 {
     return float4(((float)i) + 1.5, ((float)u) - 2.5, ((float)b) / 2, h);