Update actions/checkout action to v4 #404

Job	Run time
Scan Licenses	0s
Build Package	0s
CodeQL Analyze	3m 58s
Build docs	0s
Lint	56s
Security Lint	1m 8s
SonarCloud	37s
Test Python 3.6 - ubuntu	7s
Test Python 3.7 - ubuntu	39s
Test Python 3.8 - ubuntu	35s
Check Types	1m 25s
Test Python 3.9 - ubuntu	40s
Test Python 3.6 - windows	2m 7s
Test Python 3.7 - windows	1m 5s
Test Python 3.8 - windows	1m 11s
Test Python 3.9 - windows	1m 52s
Test Python 3.6 - macos	1m 58s
Test Python 3.7 - macos	1m 16s
Test Python 3.8 - macos	1m 1s
Test Python 3.9 - macos	49s
Test Build Python ${{ matrix.py }} - ${{ matrix.os }}	0s
Publish Package	0s
Publish Docs	0s
	21m 24s

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