Migrate Ruby 2.0.0 case in Travis to GitHub Actions.

As the CentOS 7 system Ruby is the fixed version 2.0.0, we can remove
the Ruby 2.0.0 case in Travis.

Remove `sudo: required` syntax in Travis, as the key `sudo` is deprecated
and it has no effect anymore according to the Travis "View config" page.

.github/workflows/container.yml

@@ -5,13 +5,14 @@ on: [push, pull_request]
 jobs:
   build:
     name: >-
-      ${{ matrix.distro }} ${{ matrix.image }}
+      ${{ matrix.distro }} ${{ matrix.image }} ${{ matrix.name_extra || '' }}
     runs-on: ubuntu-20.04 # focal
     continue-on-error: ${{ matrix.allow-failure || false }}
     strategy:
       matrix:
         include:
-          - {distro: centos, image: 'centos:7'}
+          # CentOS 7 system Ruby is the fixed version 2.0.0.
+          - {distro: centos, image: 'centos:7', name_extra: 'ruby 2.0.0'}
           # Fedora latest stable version
           # Allow failure due to the following test failures.
           # https://github.com/brianmario/mysql2/issues/965

.travis.yml

@@ -1,4 +1,3 @@
-sudo: required
 dist: trusty
 language: ruby
 bundler_args: --without development
@@ -9,17 +8,8 @@ before_install:
   - gem update bundler
   - gem --version
   - bash ci/setup.sh
-addons:
-  hosts:
-    - mysql2gem.example.com
-  apt:
-    packages:
-    - mysql-server-5.6
-    - mysql-client-core-5.6
-    - mysql-client-5.6
 matrix:
   include:
-    - rvm: 2.0.0
     - rvm: 2.4
       env: DB=mariadb10.0
       addons: