Fix compilation on linux: always initialize ScopedZone::m_connectionId to 0.

gcc error:
public/tracy/../client/TracyScoped.hpp:102:9: error: ‘___tracy_scoped_zone.tracy::ScopedZone::m_connectionId’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
         if( GetProfiler().ConnectionId() != m_connectionId ) return;
         ^~

public/client/TracyScoped.hpp

@@ -166,7 +166,7 @@ private:
     const bool m_active;
 
 #ifdef TRACY_ON_DEMAND
-    uint64_t m_connectionId;
+    uint64_t m_connectionId = 0;
 #endif
 };