FIX Use PHP 8.3 compatible version of vfsstream (#148)

.github/workflows/ci.yml

@@ -534,7 +534,7 @@ jobs:
             # Required for any module/recipe that runs silverstripe/assets unit tests
             # Should technically be defined as composer_require_extra on individual modules, though easier just doing here
             # 1.6.10 is for --prefer-lowest and is the minimum version with php 8.1 support
-            composer require mikey179/vfsstream:^1.6.10 --dev --no-update
+            composer require mikey179/vfsstream:^1.6.11 --dev --no-update
 
             if [[ "${{ matrix.db }}" == "pgsql" ]] && ! [[ $GITHUB_REPOSITORY =~ /silverstripe-postgresql$ ]]; then
               composer require "silverstripe/postgresql:^2 || ^3" --no-update