Make constructors for upscaling explicit

Signed-off-by: Tobias Frisch <tfrisch@uni-koblenz.de>

modules/upscaling/include/vkcv/upscaling/BilinearUpscaling.hpp

@@ -7,7 +7,7 @@ namespace vkcv::upscaling {
 	class BilinearUpscaling : public Upscaling {
 	private:
 	public:
-		BilinearUpscaling(Core& core);
+		explicit BilinearUpscaling(Core& core);
 		
 		void recordUpscaling(const CommandStreamHandle& cmdStream,
 							 const ImageHandle& input,

modules/upscaling/include/vkcv/upscaling/Upscaling.hpp

@@ -10,7 +10,7 @@ namespace vkcv::upscaling {
 		Core& m_core;
 	
 	public:
-		Upscaling(Core& core);
+		explicit Upscaling(Core& core);
 		
 		~Upscaling() = default;