Bugfix Interface return type

Author: nyamsprod

src/Domain.php

@@ -474,7 +474,7 @@ public function isPrivate(): bool
     /**
      * {@inheritdoc}
      */
-    public function toAscii(): self
+    public function toAscii(): DomainInterface
     {
         if (null === $this->domain) {
             return $this;
@@ -491,7 +491,7 @@ public function toAscii(): self
     /**
      * {@inheritdoc}
      */
-    public function toUnicode(): self
+    public function toUnicode(): DomainInterface
     {
         if (null === $this->domain || false === strpos($this->domain, 'xn--')) {
             return $this;

src/PublicSuffix.php

@@ -316,7 +316,7 @@ public function isPrivate(): bool
     /**
      * {@inheritdoc}
      */
-    public function toAscii(): self
+    public function toAscii(): DomainInterface
     {
         if (null === $this->publicSuffix) {
             return $this;
@@ -333,7 +333,7 @@ public function toAscii(): self
     /**
      * {@inheritdoc}
      */
-    public function toUnicode(): self
+    public function toUnicode(): DomainInterface
     {
         if (null === $this->publicSuffix || false === strpos($this->publicSuffix, 'xn--')) {
             return $this;