[CI] Drops Ruby 2.5 from test matrix

Author: picandocodigo

.ci/test-matrix.yml

@@ -8,7 +8,6 @@ RUBY_TEST_VERSION:
 - 3.0
 - 2.7
 - 2.6
-- 2.5
 
 TEST_SUITE:
 - free
@@ -21,5 +20,3 @@ exclude:
     RUBY_TEST_VERSION: 2.7
   - STACK_VERSION: 8.0.0-SNAPSHOT
     RUBY_TEST_VERSION: 2.6
-  - STACK_VERSION: 8.0.0-SNAPSHOT
-    RUBY_TEST_VERSION: 2.5

.github/workflows/7.17.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '2.5', '2.6', '2.7', '3.0', '3.1', 'jruby-9.3' ]
+        ruby: [ '2.6', '2.7', '3.0', '3.1', 'jruby-9.3' ]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2