fix(core): discover vendor directory first on all platforms (#1535)

Author: TheRealMrG

packages/core/src/Kernel/LoadConfig.php

@@ -58,7 +58,7 @@ public function find(): array
             })
             ->sortByCallback(function (string $path1, string $path2) use ($suffixes): int {
                 $getPriority = fn (string $path): int => match (true) {
-                    Str\contains($path, '/vendor/') => 0,
+                    Str\contains($path, DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR) => 0,
                     Str\contains($path, $suffixes['testing']) => 6,
                     Str\contains($path, $suffixes['development']) => 5,
                     Str\contains($path, $suffixes['production']) => 4,