fix: provide restrictions property to query

fixes #204

Author: gurza

src/CompaniesHouse/UriBuilders/SearchCompanyUriBuilder.cs

@@ -12,7 +12,7 @@ protected override string BuildQuery(SearchCompanyRequest request)
     {
         var query = base.BuildQuery(request);
 
-        if (string.IsNullOrWhiteSpace(request.Restrictions))
+        if (!string.IsNullOrWhiteSpace(request.Restrictions))
         {
             query += "&restrictions=" + request.Restrictions;
         }