Update GitHub Actions workflow: change CI skip condition to pull request body and reduce Ruby version matrix

Author: elalemanyo

.github/workflows/build.yml

@@ -8,11 +8,11 @@ on:
       - main
 jobs:
   build:
-    if: "!contains(github.event.head_commit.message, '[skip ci]')"
+    if: !contains(github.event.pull_request.body, '[skip ci]')
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: [ '2.6', '3.0', '3.2', '3.3.4', '3.3.5' ]
+        ruby: [ '3.0', '3.3.4', '3.3.5' ]
     steps:
     - uses: actions/checkout@v3
     - uses: ruby/setup-ruby@v1