ADD new test

[AntonioCarta]

add a bunch of tests needed to ensure the new strategies are not breaking anything. Should fix the tests breaking in #905

[ContinualAI-bot]

Oh no! It seems there are some PEP8 errors! 😕
Don't worry, you can fix them! 💪
Here's a report about the errors and where you can find them:

tests/training/test_supervised_regression.py:53:25: E251 unexpected spaces around keyword / parameter equals
tests/training/test_supervised_regression.py:53:27: E251 unexpected spaces around keyword / parameter equals
2       E251 unexpected spaces around keyword / parameter equals

[coveralls]

Pull Request Test Coverage Report for Build 1811463576

• 307 of 377 (81.43%) changed or added relevant lines in 8 files are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.5%) to 77.866%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
avalanche/benchmarks/utils/data_loader.py	14	24	58.33%
tests/training/test_supervised_regression.py	225	285	78.95%

Files with Coverage Reduction	New Missed Lines	%
avalanche/models/dynamic_modules.py	1	95.37%
avalanche/benchmarks/utils/data_loader.py	2	87.97%

Totals
Change from base Build 1796153147:	0.5%
Covered Lines:	11620
Relevant Lines:	14923

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💛 - Coveralls