Upcoming additionals versions requires ruby 2.6 -> drop ruby 2.5 tests and add ruby 3.0 tests

Author: alexandermeindl

Diff for: .github/workflows/test.yml

@@ -10,12 +10,16 @@ jobs:
 
     strategy:
       matrix:
-        ruby: ['2.7', '2.6', '2.5']
+        ruby: ['2.7', '2.6', '3.0']
         redmine: ['4.1-stable', '4.2-stable', 'master']
         db: ['postgres', 'mysql']
         exclude:
           - ruby: 2.7
             redmine: 4.1-stable
+          - ruby: '3.0'
+            redmine: 4.1-stable
+          - ruby: '3.0'
+            redmine: 4.2-stable
       fail-fast: false
 
     services: