old_contents: from conans import ConanFile
  
  class OSSCoreTestsConan(ConanFile):
      settings = "os", "compiler", "build_type", "arch"
      generators = "cmake_find_package"
  
      def requirements(self):
          self.requires("catch2/2.13.3")
  
new_contents: from conans import ConanFile
  
  class OSSCoreTestsConan(ConanFile):
      settings = "os", "compiler", "build_type", "arch"
      generators = "cmake_find_package"
  
      def requirements(self):
          self.requires("catch2/2.13.3")
          self.requires("nlohmann_json/3.9.1")
  
subject: add nlohmann_json/3.9.1