Bump to NLPModels 0.21 (#124)

Author: tmigot

Project.toml

@@ -14,7 +14,7 @@ SparseMatricesCOO = "fa32481b-f100-4b48-8dc8-c62f61b13870"
 
 [compat]
 LinearOperators = "2.2.2, 2.3"
-NLPModels = "0.18, 0.19, 0.20"
+NLPModels = "0.18, 0.19, 0.20, 0.21"
 NLPModelsModifiers = "0.6, 0.7"
 Requires = "0.3, 0.4, 0.5, 1.0"
 SolverCore = "0.3"