Bug: Some examples weren't updated to 2.0 in their requirements

[jackiekazil]

Bug: Some examples weren't updated to 2.0 in their requirements #76. Forrest fire was updated in #75
This commit shows that there are others where requirements aren't updated, but the code was.
428c900

Things that need to happen...

• Identify which ones had code changed but didn't have requirements updated
• Test the code against 2+
• Update the requirements as appropriate and file bugs for the rest.

It is assumed that all the models with the requirements.txt file updated have been tested successfully. Below is a list of models where the requirements.txt was not updated to 2.0, but there were changes in the commit mentions above.

Models to check

• caching and replay
• color_patches Fix requirements to update multiple examples to 2.0 #77
• conways game of life Fix requirements to update multiple examples to 2.0 #77
• epstein civil violence Fix requirements to update multiple examples to 2.0 #77
• forest fire Fix forest fire to update requirements to mesa 2.0. #75
• sugar_scape_g1mt