minor #20611 Use PHP 8.4 (OskarStark)

This PR was merged into the 6.4 branch.

Discussion
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Use PHP 8.4

Commits
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827ea34 Use PHP 8.4

Author: OskarStark

.github/workflows/ci.yaml

@@ -26,9 +26,8 @@ jobs:
             -   name: "Set-up PHP"
                 uses: shivammathur/setup-php@v2
                 with:
-                    php-version: 8.1
+                    php-version: 8.4
                     coverage: none
-                    tools: "composer:v2"
 
             -   name: Get composer cache directory
                 id: composercache
@@ -93,7 +92,7 @@ jobs:
             -   name: Set-up PHP
                 uses: shivammathur/setup-php@v2
                 with:
-                    php-version: 8.1
+                    php-version: 8.4
                     coverage: none
 
             -   name: Fetch branch from where the PR started