Drop ChainRulesCore v0.9 support, use NoTangent()

Author: mkitti

Project.toml

@@ -17,7 +17,7 @@ WoodburyMatrices = "efce3f68-66dc-5838-9240-27a6d6f5f9b6"
 
 [compat]
 AxisAlgorithms = "0.3, 1"
-ChainRulesCore = "0.9, 0.10"
+ChainRulesCore = "0.10"
 OffsetArrays = "0.10, 0.11, 1.0.1"
 Ratios = "0.3, 0.4"
 Requires = "1.1"

src/chainrules/chainrules.jl

@@ -6,7 +6,7 @@ ChainRulesCore.jl `rrule` for integration with automatic differentiation librari
 function ChainRulesCore.rrule(itp::AbstractInterpolation, x...)
     y = itp(x...)
     function pullback(Δy)
-        (ChainRulesCore.DoesNotExist(), Δy * Interpolations.gradient(itp, x...))
+        (ChainRulesCore.NoTangent(), Δy * Interpolations.gradient(itp, x...))
     end
     y, pullback
 end