Fix comparison of zero values of type float32 and float64 in simulation deactivation

[IshaanDesai]

If the adaptivity data is zero and the coarsening tolerance is set to sys.float.min, the if condition in deactivation can lead to a false negative.

Checklist:

• I added a summary of the changes (compared to the last release) in the CHANGELOG.md.
• I will remember to squash-and-merge, providing a useful summary of the changes of this PR.