ci: use PHP 8.0 for tests

Author: ramsey

.github/workflows/continuous-integration.yml

@@ -16,8 +16,7 @@ jobs:
       - uses: "actions/checkout@v2"
       - uses: "shivammathur/setup-php@v2"
         with:
-          php-version: "7.4"
-          tools: "composer:v2"
+          php-version: "8.0"
       - run: "npm install"
       - run: "npm run all"
       - uses: "codecov/codecov-action@v1"
@@ -46,8 +45,7 @@ jobs:
       - uses: "actions/checkout@v2"
       - uses: "shivammathur/setup-php@v2"
         with:
-          php-version: "7.4"
-          tools: "composer:v2"
+          php-version: "8.0"
       - uses: ./
         with:
           dependency-versions: "${{ matrix.dependency-versions }}"