Update ptah to GDP examples #71

Job	Run time
lint/style-and-typos	2m 17s
linux/3.12	2h 0m 13s
osx/3.10	2h 0m 15s
win/3.9	14m 38s
linux/3.11/conda	25m 16s
linux/3.8/bare-env	12s
linux/3.10/mpi	8m 54s
linux/3.10/cython	23m 10s
win/3.8/pip	33m 46s
process-coverage-${{ matrix.TARGET }}	0s
	5h 48m 41s

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