Remove (final?) leftover xcodeproj #19

Job	Run time
build_and_test (04-tdd-in-the-real-world)	8m 53s
build_and_test (05-fixtures)	9m 21s
build_and_test (06-testing-static-swiftui-views)	17m 54s
build_and_test (07-testing-dynamic-swiftui-views)	7m 17s
build_and_test (08-stub)	12m 34s
build_and_test (09-json-decoding)	11m 1s
build_and_test (10-networking)	8m 21s
build_and_test (11-dependency-injection-with-environment-object)	10m 38s
build_and_test (12-spy)	10m 21s
build_and_test (13-testing-view-presentation)	11m 9s
build_and_test (14-fixing-bugs-and-changing-code)	10m 40s
build_and_test (15-fake-and-dummy)	9m 6s
build_and_test (17-appendix-b-nimble-only)	6m 8s
build_and_test (18-appendix-b-quick-and-nimble)	5m 37s
build_and_test (19-appendix-c-uikit)	5m 2s
	2h 24m 2s

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