Update build.yml

- add ruby 3.2 and 3.3
- use ubuntu-latest
- use faster/newer checkout@v4

.github/workflows/build.yml

@@ -12,11 +12,11 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-18.04, windows-2019]
-        ruby: ['2.6', '2.7', '3.0', '3.1']
+        os: [ubuntu-latest, windows-2019]
+        ruby: ['2.6', '2.7', '3.0', '3.1', '3.2', '3.3']
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}