Remove ForwardDiff 1 compat (again)

The test environment cannot be resolved with this version, 
see #195 ...
Hence, it is NEVER tested and we should not include this version in the compats.

Author: pjaap

Project.toml

@@ -82,7 +82,7 @@ ExtendableFEM = "0.9.1"
 ExtendableFEMBase = "0.7,0.8"
 ExtendableGrids = "1.11.0"
 ExtendableSparse = "1.6"
-ForwardDiff = "0.10.35, 1"
+ForwardDiff = "0.10.35"
 GridVisualize = "0.5.2,0.6.1,1"
 HypertextLiteral = "0.9.5"
 ILUZero = "0.2.0"