Implement a Generator class for the Knapsack environment which is responsible for generating the Knapsack instances. This will include the following additions:

• A generator.py script added to the knapsack folder which implements an abstract class Generator and a RandomGenerator to create a random uniform Knapsack instance.
• A generator_test.py script to test the generator.
• Modifications to env.py to include the generator in the init method and changes to conftest.py to include a DummyGenerator for testing purposes.