Build Cache for Gradle v2.18.8

[system]

What’s Changed

• Bump bitrise-build-cache-cli to v2.4.8: jitpack mirror disabled (returning 401 upstream) and gradle-mirrors activation now warns when the project uses apply(from = ...) (mirror scope-gap).

Release 2.18.8 · bitrise-steplib/bitrise-step-activate-gradle-remote-cache