CI: Update the Julia versions that are used in CI

Author: DilumAluthge

.github/workflows/ci.yml

@@ -13,9 +13,10 @@ jobs:
     strategy:
       matrix:
         version:
-          - '1.0.5'
-          - '1.5.4'
-          - '1.6.0'
+          - '1.0'  # minimum Julia version supported in Project.toml
+          - '1.6'  # previous LTS
+          - '1.10' # current LTS
+          - '1'    # automatically expands to the latest stable 1.x release
     steps:
       - uses: actions/checkout@v2
       - name: Setup Docker