Corrected a few type-hints (#8)

* Correct return type-hint in Real::toInteger

* Correct return type-hint for Integer::toReal

```
ERROR: InvalidMethodCall - php/Foo/Bar/Baz.php:63:57 - Cannot call method on float variable  (see https://psalm.dev/091)
            $this->chargeAmount->getAmount()->toReal()->toNative(),
```

* Correct construtor type-hint in Money clas

```
ERROR: InvalidArgument - php/Foo/Bar/Baz.php:564:38 - Argument 1 of ValueObjects\Money\Money::__construct expects int, ValueObjects\Number\Integer provided (see https://psalm.dev/004)
            $lowestMoney = new Money(new Integer((int)$lowestPrice), new Currency($this->catalog->getCurrencyCode()));
```

src/Money/Money.php

@@ -38,7 +38,7 @@ class Money implements ValueObjectInterface
     /**
      * Returns a Money object.
      *
-     * @param int      $amount   Amount expressed in the smallest units of $currency (e.g. cents)
+     * @param Integer  $amount   Amount expressed in the smallest units of $currency (e.g. cents)
      * @param Currency $currency Currency of the money object
      */
     public function __construct(Integer $amount, Currency $currency)

src/Number/Integer.php

@@ -69,7 +69,7 @@ public function toNative(): int
     /**
      * Returns a Real with the value of the Integer.
      *
-     * @return float
+     * @return Real
      */
     public function toReal(): Real
     {

src/Number/Real.php

@@ -111,7 +111,7 @@ public function sameValueAs(ValueObjectInterface $real): bool
      *
      * @param RoundingMode $roundingMode Rounding mode of the conversion. Defaults to RoundingMode::HALF_UP.
      *
-     * @return int
+     * @return Integer
      */
     public function toInteger(RoundingMode $roundingMode = null): Integer
     {