Add pytest timeout

[freddyaboulton]

Pull Request Description

Add timeout to identify hanging tests.

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After creating the pull request: in order to pass the release_notes_updated check you will need to update the "Future Release" section of docs/source/release_notes.rst to include this pull request by adding :pr:123.

[codecov]

Codecov Report

Merging #2374 (822453e) into main (e83bf1a) will increase coverage by 0.2%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            main   #2374     +/-   ##
=======================================
+ Coverage   99.7%   99.9%   +0.2%     
=======================================
  Files        281     281             
  Lines      24849   24849             
=======================================
+ Hits       24773   24817     +44     
+ Misses        76      32     -44     

Impacted Files	Coverage Δ
evalml/tests/pipeline_tests/test_pipelines.py	99.8% <0.0%> (+0.3%)	⬆️
...del_understanding_tests/test_partial_dependence.py	100.0% <0.0%> (+0.3%)	⬆️
...lml/tests/model_understanding_tests/test_graphs.py	100.0% <0.0%> (+0.3%)	⬆️
evalml/utils/gen_utils.py	99.6% <0.0%> (+0.5%)	⬆️
evalml/automl/automl_search.py	99.9% <0.0%> (+0.6%)	⬆️
...understanding_tests/test_permutation_importance.py	100.0% <0.0%> (+0.6%)	⬆️
evalml/tests/utils_tests/test_logger.py	100.0% <0.0%> (+0.6%)	⬆️
...lml/tests/automl_tests/test_iterative_algorithm.py	100.0% <0.0%> (+0.9%)	⬆️
evalml/tests/component_tests/test_components.py	100.0% <0.0%> (+1.0%)	⬆️
...ests/automl_tests/test_automl_search_regression.py	100.0% <0.0%> (+1.0%)	⬆️
... and 6 more

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