Update CI

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: 'github-actions'
+    directory: '/'
+    schedule:
+      interval: 'weekly'

.github/workflows/linux.yml → .github/workflows/unit-test.yml

@@ -1,4 +1,4 @@
-name: Test on Ubuntu
+name: Test
 on:
   push:
     branches: [master]
@@ -10,9 +10,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '3.1', '3.0', '2.7', '2.6' ]
-        os:
-          - ubuntu-latest
+        ruby: [ '3.2', '3.1', '3.0', '2.7' ]
+        os: [ 'ubuntu-latest', 'macOS-latest', 'windows-latest' ]
+        # It should be removed after RubyInstaller 3.2 is available on setup-ruby
+        exclude:
+          - os: windows-latest
+            ruby: 3.2
     name: Ruby ${{ matrix.ruby }} unit testing on ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2