Recently, web-de was re-recorded with mitm7 (bug 1796649). However this patch series modifies `alt-serverplayback.py` for mitm8 compatibility and doesn't work with mitm7 anymore. Given that currently web-de is the only android test using mitm7, it makes sense to bump the `playback_version` up to mitmproxy 8 rather than maintaining another `serverplayback`-like file for the sake of mitm7. And due to forward compatibility, there is no need to re-record web-de in 8 at this time.
Differential Revision: https://phabricator.services.mozilla.com/D161679