Fix missing private modifier

Author: Exanite

.silktouch/d48a9fc4a502f7c6.stout

@@ -177,6 +177,7 @@ private IEnumerable<MemberDeclarationSyntax> RewriteMember(MemberDeclarationSynt
                 .WithExplicitInterfaceSpecifier(null)
                 .WithIdentifier(Identifier(privateMethodName))
                 .WithModifiers([
+                    Token(SyntaxKind.PrivateKeyword),
                     ..member.Modifiers.Where(modifier =>
                         !SyntaxFacts.IsAccessibilityModifier(modifier.Kind()))
                 ]);