Run tests on PHP 8.4 (#136)

* Run tests on PHP 8.4

* Use the latest composer in tests

Packagist ends support for Composer 1.x soon anyway
https://blog.packagist.com/shutting-down-packagist-org-support-for-composer-1-x/

* Don't use matrix to specify `runs-on: ubuntu-latest`

* Test with --prefer-lowest also in PHP 8.1

Newer PHP versions require newer dependencies, tests would fail.

.github/workflows/main.yaml

@@ -13,7 +13,6 @@ on:
 env:
   extensions: "json, pdo_mysql, pdo_sqlite, intl"
   cache-version: "1"
-  composer-version: "v1"
   composer-install: "composer update --no-interaction --no-progress --no-suggest --prefer-dist --prefer-stable"
 
 jobs:
@@ -45,7 +44,7 @@ jobs:
         with:
           php-version: "8.0"
           extensions: "${{ env.extensions }}"
-          tools: "composer:${{ env.composer-version }}"
+          tools: "composer"
 
       - name: "Setup problem matchers for PHP"
         run: 'echo "::add-matcher::${{ runner.tool_cache }}/php.json"'
@@ -107,7 +106,7 @@ jobs:
         with:
           php-version: "8.1"
           extensions: "${{ env.extensions }}"
-          tools: "composer:${{ env.composer-version }}"
+          tools: "composer"
 
       - name: "Setup problem matchers for PHP"
         run: 'echo "::add-matcher::${{ runner.tool_cache }}/php.json"'
@@ -131,7 +130,7 @@ jobs:
 
   tests:
     name: "Tests"
-    runs-on: "${{ matrix.operating-system }}"
+    runs-on: "ubuntu-latest"
     services:
       mariadb:
         image: "mariadb:10.4"
@@ -149,12 +148,12 @@ jobs:
 
     strategy:
       matrix:
-        php-version: [ "8.0", "8.1", "8.2", "8.3" ]
-        operating-system: [ "ubuntu-latest" ]
+        php-version: [ "8.0", "8.1", "8.2", "8.3", "8.4" ]
         composer-args: [ "" ]
         include:
           - php-version: "8.0"
-            operating-system: "ubuntu-latest"
+            composer-args: "--prefer-lowest"
+          - php-version: "8.1"
             composer-args: "--prefer-lowest"
       fail-fast: false
 
@@ -182,7 +181,7 @@ jobs:
         with:
           php-version: "${{ matrix.php-version }}"
           extensions: "${{ env.extensions }}"
-          tools: "composer:${{ env.composer-version }}"
+          tools: "composer"
 
       - name: "Setup problem matchers for PHP"
         run: 'echo "::add-matcher::${{ runner.tool_cache }}/php.json"'
@@ -250,7 +249,7 @@ jobs:
           php-version: "8.0"
           coverage: "xdebug"
           extensions: "${{ env.extensions }}"
-          tools: "composer:${{ env.composer-version }}"
+          tools: "composer"
 
       - name: "Setup problem matchers for PHP"
         run: 'echo "::add-matcher::${{ runner.tool_cache }}/php.json"'