title: conan dependency conflict when importing package hdf5/1.10.6 which depends on zlib/1.2.11
body: <p>I try to add the package hdf5/1.10.6 in my application. I've got the following error.</p>
  
  <pre><code>[build] ERROR: Conflict in hdf5/1.10.6
  [build]     Requirement zlib/1.2.11 conflicts with already defined zlib/1.2.11@conan/stable
  [build]     To change it, override it in your base requirements
  [build] CMake Error at build/conan.cmake:402 (message):
  [build]   Conan install failed='1'
  [build] Call Stack (most recent call first):
  [build]   build/conan.cmake:497 (conan_cmake_install)
  [build]   CMakeLists.txt:12 (conan_cmake_run)
  </code></pre>
  
  <p>There is an existing package that depends on 'zlib/1.2.11@conan/stable'. And hdf5/1.10.5 depends on 'zlib/1.2.11'. </p>
  
  <p>How can I resolve this conflict? Is there a way to specify zlib/1.2.11@conan/stable = zlib/1.2.11?</p>
  
  <p>thx</p>