add a datastack arg to the export-py CLI command. #3416

Job	Run time
Check HISTORY RST syntax	11s
Check for syntax errors	9s
Build binaries (macos-latest)	1m 19s
Build sampledata archives	1m 25s
Run model tests (3.8, windows-latest)	1m 16s
Build binaries (windows-latest)	1m 5s
Run model tests (3.8, macos-latest)	1m 17s
Check sdist (3.8, windows-latest)	1m 3s
Run model tests (3.9, windows-latest)	1m 16s
Check sdist (3.8, macos-latest)	1s
Run Workbench Tests (windows-latest)	1m 3s
Validate Sampledata & User Guide	1m 2s
Run model tests (3.9, macos-latest)	1m 24s
Check sdist (3.9, windows-latest)	1m 4s
Run model tests (3.10, windows-latest)	1m 5s
Check sdist (3.9, macos-latest)	1s
Run model tests (3.10, macos-latest)	1m 3s
Check sdist (3.10, windows-latest)	1m 3s
Run model tests (3.11, windows-latest)	1m 5s
Run Workbench Tests (macos-latest)	1s
Check sdist (3.10, macos-latest)	1s
Run model tests (3.11, macos-latest)	1m 18s
Check sdist (3.11, windows-latest)	1m 5s
Check sdist (3.11, macos-latest)	1s
	20m 18s

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