phpExtensions.soap: add phpExtensions.session as internal deps.

Context: php/php-src#14362

Author: drupol

pkgs/top-level/php-packages.nix

@@ -620,6 +620,7 @@ in {
             "--enable-soap"
           ];
           doCheck = false;
+          internalDeps = [ php.extensions.session ];
         }
         {
           name = "sockets";