libobs-d3d11: Remove "support" for feature level 9.3

Feature Level 9.3 appears to never have actually worked because shaders
are compiled as straight 4_0 instead of 4_0_level_9_3. That being the
case, baseline against 10_0 instead.

libobs-d3d11/d3d11-rebuild.cpp

@@ -273,7 +273,6 @@ const static D3D_FEATURE_LEVEL featureLevels[] = {
 	D3D_FEATURE_LEVEL_11_0,
 	D3D_FEATURE_LEVEL_10_1,
 	D3D_FEATURE_LEVEL_10_0,
-	D3D_FEATURE_LEVEL_9_3,
 };
 
 void gs_device::RebuildDevice()

libobs-d3d11/d3d11-subsystem.cpp

@@ -229,7 +229,6 @@ const static D3D_FEATURE_LEVEL featureLevels[] = {
 	D3D_FEATURE_LEVEL_11_0,
 	D3D_FEATURE_LEVEL_10_1,
 	D3D_FEATURE_LEVEL_10_0,
-	D3D_FEATURE_LEVEL_9_3,
 };
 
 /* ------------------------------------------------------------------------- */
@@ -355,7 +354,7 @@ void gs_device::InitDevice(uint32_t adapterIdx)
 {
 	wstring adapterName;
 	DXGI_ADAPTER_DESC desc;
-	D3D_FEATURE_LEVEL levelUsed = D3D_FEATURE_LEVEL_9_3;
+	D3D_FEATURE_LEVEL levelUsed = D3D_FEATURE_LEVEL_10_0;
 	HRESULT hr = 0;
 
 	adpIdx = adapterIdx;