Add new workflow to test dart-dio samples #6

Job	Run time
test (ubuntu-latest, 2.19.0, samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-j...	3m 37s
test (ubuntu-latest, 3.6.0, samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-js...	3m 37s
test (windows-latest, 3.6.0, samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-j...	45s
test (windows-latest, 2.19.0, samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-...	3m 37s
	11m 36s

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