run CI on default CPU arch for each OS

.github/workflows/CI.yml

@@ -4,27 +4,20 @@ on:
   - pull_request
 jobs:
   test:
-    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }}
+    name: Julia ${{ matrix.version }} - ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
         version:
-          #- '1.0'
           - '1'
-          #- 'nightly'
         os:
           - ubuntu-latest
-          #- macOS-latest
-          #- windows-latest
-        arch:
-          - x64
     steps:
       - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
-          arch: ${{ matrix.arch }}
       - uses: actions/cache@v1
         env:
           cache-name: cache-artifacts