minor symfony#2442 [Site] Upgrade PHP8.4 on psh (smnandre)

This PR was merged into the 2.x branch.

Discussion
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[Site] Upgrade PHP8.4 on psh

Commits
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5f556c1 [Site] Upgrade PHP8.4 on psh

Author: javiereguiluz

ux.symfony.com/.platform.app.yaml

@@ -1,10 +1,10 @@
 name: app
 
-type: php:8.3
+type: php:8.4
 
 dependencies:
     php:
-        composer/composer: "^2"
+        composer/composer: "^2.8"
 
 build:
     flavor: none