increasing ci julia version to 1.6 and including 1.3 in addition

Author: schlichtanders

.github/workflows/ci.yml

@@ -9,7 +9,8 @@ jobs:
     strategy:
       matrix:
         version:
-          - '1.4'
+          - '1.3'
+          - '1.6'
           - 'nightly'
         os:
           - ubuntu-latest