ci: move PHP 8.1 to the main list of matrix versions

Author: ramsey

.github/workflows/continuous-integration.yml

@@ -22,7 +22,7 @@ jobs:
           coverage: "none"
 
       - name: "Install dependencies (Composer)"
-        uses: "ramsey/composer-install@v1"
+        uses: "ramsey/composer-install@v2"
 
       - name: "Check syntax (php-parallel-lint)"
         shell: "bash"
@@ -46,7 +46,7 @@ jobs:
           coverage: "none"
 
       - name: "Install dependencies (Composer)"
-        uses: "ramsey/composer-install@v1"
+        uses: "ramsey/composer-install@v2"
 
       - name: "Statically analyze code (PHPStan)"
         shell: "bash"
@@ -70,7 +70,7 @@ jobs:
           coverage: "none"
 
       - name: "Install dependencies (Composer)"
-        uses: "ramsey/composer-install@v1"
+        uses: "ramsey/composer-install@v2"
 
       - name: "Analyze security of code (Psalm)"
         shell: "bash"
@@ -96,7 +96,7 @@ jobs:
           ini-values: "memory_limit=-1"
 
       - name: "Install dependencies (Composer)"
-        uses: "ramsey/composer-install@v1"
+        uses: "ramsey/composer-install@v2"
 
       - name: "Run unit tests (PHPUnit)"
         shell: "bash"
@@ -115,18 +115,14 @@ jobs:
         php-version:
           - "7.4"
           - "8.0"
+          - "8.1"
         operating-system:
           - "macos-latest"
           - "ubuntu-latest"
           - "windows-latest"
         dependencies:
           - "lowest"
           - "highest"
-        include:
-          - php-version: "8.1"
-            operating-system: "ubuntu-latest"
-            dependencies: "highest"
-            composer-options: "--ignore-platform-req=php"
 
     steps:
       - name: "Configure Git (for Windows)"