reports/bisect: use urlparse.urljoin to construct log URLs
reports/bisect: use urlparse.urljoin to construct log URLs

Use the safer urlparse.urljoin() method when constructing log URLs in
the bisection email reports.

Signed-off-by: Guillaume Tucker <e7e20b7c30f19d4ca6b81319ef81bf200369d137@collabora.com>

kernelci/kernelci-backend,kernelci/kernelci-backend