obs-text: Do not reset blend state

Similar to the parent commit, do not reset the blend state if the source
is not marked as a custom drawn source.  Filters applied won't have the
correct blend state and the alpha edges of the text will be partially
black.

plugins/obs-text/gdiplus/obs-text.cpp

@@ -787,7 +787,6 @@ inline void TextSource::Render(gs_effect_t *effect)
 	if (!tex)
 		return;
 
-	gs_reset_blend_state();
 	gs_effect_set_texture(gs_effect_get_param_by_name(effect, "image"), tex);
 	gs_draw_sprite(tex, 0, cx, cy);
 }