pypi.bbclass: use new pypi UPSTREAM_CHECK_URI

Upstream https://pypi.python.org/pypi/${PYPI_PACKAGE}/
redirects to https://pypi.org/project/${PYPI_PACKAGE}/



Signed-off-by: Tim Orling <timothy.t.orling@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>