minor #17712 Bump versions on the build script (fabpot)

This PR was merged into the 5.4 branch.

Discussion
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Bump versions on the build script

As PHP 7.4 is not maintained anymore, let's use 8.1 as the minimum version.
I've also bumped the deps to 6.2.

Commits
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b07c069 Bump versions on the build script

Author: javiereguiluz

_build/build.php

@@ -20,7 +20,7 @@
 
         $outputDir = __DIR__.'/output';
         $buildConfig = (new BuildConfig())
-            ->setSymfonyVersion('4.4')
+            ->setSymfonyVersion('5.4')
             ->setContentDir(__DIR__.'/..')
             ->setOutputDir($outputDir)
             ->setImagesDir(__DIR__.'/output/_images')

_build/composer.json

@@ -3,7 +3,7 @@
     "prefer-stable": true,
     "config": {
         "platform": {
-            "php": "7.4.14"
+            "php": "8.1.0"
         },
         "preferred-install": {
             "*": "dist"
@@ -14,9 +14,9 @@
         }
     },
     "require": {
-        "php": ">=7.4",
-        "symfony/console": "^5.4",
-        "symfony/process": "^5.4",
+        "php": ">=8.1",
+        "symfony/console": "^6.2",
+        "symfony/process": "^6.2",
         "symfony-tools/docs-builder": "^0.18"
     }
 }