Add PostgreSQL Support (#3)

Reviewed-on: #3

src/AutoId.php

@@ -41,11 +41,12 @@ enum AutoId
     /**
      * Generate a random string ID
      *
+     * @param int|null $length The length of string to generate (optional; defaults to configured ID string length)
      * @return string A string filled with the hexadecimal representation of random bytes
      * @throws RandomException If an appropriate source of randomness cannot be found
      */
-    public static function generateRandom(): string
+    public static function generateRandom(?int $length = null): string
     {
-        return bin2hex(random_bytes(Configuration::$idStringLength / 2));
+        return bin2hex(random_bytes(($length ?? Configuration::$idStringLength) / 2));
     }
 }