Fix 8.0 deps

Author: dantleech

lib/Domain/ClassNameCandidates.php

@@ -5,6 +5,7 @@
 use IteratorAggregate;
 use ArrayIterator;
 use RuntimeException;
+use Traversable;
 
 final class ClassNameCandidates implements IteratorAggregate
 {
@@ -22,7 +23,7 @@ public static function fromClassNames(array $classNames)
         return new self($classNames);
     }
 
-    public function getIterator()
+    public function getIterator(): Traversable
     {
         return new ArrayIterator(array_values($this->classNames));
     }

lib/Domain/FilePathCandidates.php

@@ -5,6 +5,7 @@
 use IteratorAggregate;
 use RuntimeException;
 use ArrayIterator;
+use Traversable;
 
 final class FilePathCandidates implements IteratorAggregate
 {
@@ -53,7 +54,7 @@ public function noneFound(): bool
         return empty($this->filePaths);
     }
 
-    public function getIterator()
+    public function getIterator(): Traversable
     {
         return new ArrayIterator($this->filePaths);
     }