add julia version upper bound for CI

Author: yuehhua

.github/workflows/CI.yml

@@ -4,6 +4,11 @@ env:
 on:
   - push
   - pull_request
+
+defaults:
+  run:
+    shell: bash
+
 jobs:
   test:
     name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
@@ -13,9 +18,10 @@ jobs:
       matrix:
         version:
           - '1.6'
+          - '1'
+          - 'nightly'
         os:
           - ubuntu-latest
-          # - windows-latest
         arch:
           - x64
     steps: