Enzyme: mark device_sync as non-differentiable (#2605)

[only downstream]

Author: wsmoses

ext/EnzymeCoreExt.jl

@@ -25,6 +25,9 @@ end
 function EnzymeCore.EnzymeRules.inactive_noinl(::typeof(CUDA.is_pinned), args...)
     return nothing
 end
+function EnzymeCore.EnzymeRules.inactive_noinl(::typeof(CUDA.device_synchronize), args...)
+    return nothing
+end
 function EnzymeCore.EnzymeRules.inactive(::typeof(CUDA.launch_configuration), args...; kwargs...)
     return nothing
 end