* guix/import/pypi.scm (find-project-url): New function.
(make-pypi-sexp): Use find-project-url.
* tests/pypi.scm (foo-json): New procedure.
(test-json-1, test-json-2): Define in terms of it.
("find-project-url, with numpy", "find-project-url, uWSGI"):
("find-project-url, flake8-array-spacing")
("find-project-url, foo/goo"): New tests.
Co-authored-by: Ludovic Courtès <ludo@gnu.org>