Improve CI - use up-to-date Ruby, run half of checks per commit, schedule checks (#22)

Author: PetrHeinz

.github/workflows/main.yml

@@ -1,24 +1,29 @@
 name: build
 
-on: [push, pull_request]
+on:
+  push:
+  schedule:
+    - cron: '20 5 * * 1'
+  workflow_dispatch:
 
 jobs:
   test:
-
     runs-on: ubuntu-20.04
 
     strategy:
+      fail-fast: false
+
       matrix:
         ruby-version:
-          - 3.2.1
-          - 3.1.2
-          - 3.0.0
-          - 2.7.2
-          - 2.6.6
-          - 2.5.8
-          - 2.4.10
-          - 2.3.8
-          - 2.2.10
+          - 3.2
+          - 3.1
+          - 3.0
+          - 2.7
+          - 2.6
+          - 2.5
+          - 2.4
+          - 2.3
+          - 2.2
           - jruby-9.4.3.0
           - jruby-9.2.14.0
           - truffleruby-23.0.0