[TypeDeclaration] Set minimum php version for AddReturnTypeDeclaratio…

…nBasedOnParentClassMethodRector to php 7.0 (#4647)

rules/TypeDeclaration/Rector/ClassMethod/AddReturnTypeDeclarationBasedOnParentClassMethodRector.php

@@ -37,7 +37,7 @@ public function __construct(
 
     public function provideMinPhpVersion(): int
     {
-        return PhpVersionFeature::FATAL_ERROR_ON_INCOMPATIBLE_METHOD_SIGNATURE;
+        return PhpVersionFeature::SCALAR_TYPES;
     }
 
     public function getRuleDefinition(): RuleDefinition