Update some DeprecationWarnings to note they are removed in Mesa 3.1

[EwoutH]

This improves some of the DeprecationWarnings to make it explicit that certain features will be removed in Mesa 3.1. This communicated this clearly in line with our recommend upgrade strategy.

Features to already deprecated to be removed in Mesa 3.1:

1. Time Module: The entire Time module, including all schedulers, is deprecated and will be removed. Replacement with AgentSet functionality is recommended.
2. Parameter n in AgentSet.select: The n parameter is deprecated; use at_most instead.
3. return_results in AgentSet.do: The return_results option is deprecated; use AgentSet.do for return_results=False and AgentSet.map for return_results=True.
4. Model's next_id() method: model.next_id() is deprecated as agents now track their unique IDs automatically.
5. get_agents_of_type in Model: Model.get_agents_of_type() is deprecated; use the agents_by_type property instead.
6. initialize_data_collector() method: This method is deprecated; directly use the DataCollector class by setting self.datacollector = DataCollector(...).
7. DiscreteEventScheduler: This class is removed, and users should use the functionality provided by experimental.devs.

Note this does not add new deprecations, is just updates some to message more clearly when they get removed.

[quaquel]

Just a quick clarifying questions: what stuff can we delete in 3.1?

I'll review the stuff hopefully later today.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 +0.2% [-0.1%, +0.5%]	🔵 +1.9% [+1.8%, +2.1%]
BoltzmannWealth	large	🔵 -0.1% [-0.5%, +0.3%]	🔵 +1.7% [+1.4%, +2.1%]
Schelling	small	🔵 +0.2% [-0.2%, +0.5%]	🔵 +0.6% [+0.4%, +0.8%]
Schelling	large	🔵 +0.4% [+0.2%, +0.6%]	🔵 +0.2% [-0.3%, +0.7%]
WolfSheep	small	🔵 +0.0% [-0.1%, +0.2%]	🔵 -0.2% [-0.4%, -0.0%]
WolfSheep	large	🔵 +0.3% [+0.0%, +0.5%]	🔵 +0.3% [+0.2%, +0.5%]
BoidFlockers	small	🔵 -0.3% [-0.6%, -0.0%]	🔵 -0.4% [-1.1%, +0.2%]
BoidFlockers	large	🔵 -1.0% [-1.9%, -0.2%]	🔵 +0.4% [-0.1%, +1.0%]

[EwoutH]

what stuff can we delete in 3.1?

• Anything that's already deprecated (before 3.0.0 got tagged)
• Anything that's experimental
• Anything else that doesn't break user API

I would like to get out 3.0.1 fast and ideally have this in it.

[EwoutH]

Merging this and releasing 3.0.1.

[quaquel]

looks good