Remove RedMica3.0 from the test target

Author: ishikawa999

.github/workflows/test.yml

@@ -11,9 +11,6 @@ jobs:
     strategy:
       matrix:
         include:
-          - redmine-repository: 'redmica/redmica'
-            redmine-version: 'stable-3.0'
-            ruby-version: '3.3'
           - redmine-repository: 'redmica/redmica'
             redmine-version: 'master'
             ruby-version: '3.3'