Fixed incorrect reference in DistributionsAD extension (#299) #547

Job	Run time
test (1.6, ubuntu-latest, x64, ForwardDiff)	3m 33s
test (1.6, ubuntu-latest, x64, Tracker)	3m 16s
test (1.6, ubuntu-latest, x64, ReverseDiff)	3m 54s
test (1.6, ubuntu-latest, x64, Zygote)	4m 39s
test (1.6, macOS-latest, x64, ForwardDiff)	3m 59s
test (1.6, macOS-latest, x64, Tracker)	3m 46s
test (1.6, macOS-latest, x64, ReverseDiff)	7m 10s
test (1.6, macOS-latest, x64, Zygote)	10m 4s
test (1, ubuntu-latest, x64, ForwardDiff)	2m 26s
test (1, ubuntu-latest, x64, Tracker)	2m 10s
test (1, ubuntu-latest, x64, ReverseDiff)	2m 27s
test (1, ubuntu-latest, x64, Zygote)	2m 51s
test (1, macOS-latest, x64, ForwardDiff)	2m 46s
test (1, macOS-latest, x64, Tracker)	2m 45s
test (1, macOS-latest, x64, ReverseDiff)	3m 9s
test (1, macOS-latest, x64, Zygote)	3m 59s
	1h 2m 54s

Provide feedback