build.yml in magro-0.5.0

- old
+ new

@@ -5,10 +5,10 @@
 jobs:
   build:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        ruby: [ '2.5', '2.6', '2.7', '3.0' ]
+        ruby: [ '2.6', '2.7', '3.0' ]
     steps:
       - uses: actions/checkout@v2
       - name: Install libpng and libjpeg
         run: sudo apt-get install -y libpng-dev libjpeg-dev
       - name: Set up Ruby ${{ matrix.ruby }}