Revert "Workaroud to address apt-get update at GitHub Actions"

.github/workflows/rubocop.yml

@@ -14,7 +14,6 @@ jobs:
         ruby-version: 2.6.x
     - name: Install required package
       run: |
-        sudo rm -f /etc/apt/sources.list.d/dotnetdev.list /etc/apt/sources.list.d/microsoft-prod.list
         sudo apt-get update
         sudo apt-get install libmysqlclient-dev libpq-dev libsqlite3-dev libncurses5-dev
     - name: Cache gems