debug_utils: Make BreakpointObserver class' constructor explicit

Avoids implicit conversions.

src/video_core/debug_utils/debug_utils.h

@@ -46,7 +46,7 @@ public:
     class BreakPointObserver {
     public:
         /// Constructs the object such that it observes events of the given DebugContext.
-        BreakPointObserver(std::shared_ptr<DebugContext> debug_context)
+        explicit BreakPointObserver(std::shared_ptr<DebugContext> debug_context)
             : context_weak(debug_context) {
             std::unique_lock<std::mutex> lock(debug_context->breakpoint_mutex);
             debug_context->breakpoint_observers.push_back(this);