bump julia compat to 1.6

Author: ablaom

.github/workflows/CI.yml

@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - '1.4'
+          - '1.6'
           - '1'
         os:
           - ubuntu-latest

Project.toml

@@ -14,4 +14,4 @@ Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Distributions = "0.25"
 MLJBase = "0.18, 0.19, 0.20, 0.21"
 MLJTuning = "0.6, 0.7"
-julia = "1.4"
+julia = "1.6"