Roll expect_tests to 0.2.6.
Roll expect_tests to 0.2.6.

This removes the '.py' feature.

R=eseidel@chromium.org, stip@chromium.org
BUG=

Review URL: https://codereview.chromium.org/466913003

nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra