Note that, as part of adding this packages to the automated vendoring
system, some dependencies were automatically added - most notably,
dependencies of `taskcluster` that become visible with Python 3.6+.
Also, adds `**/.git` to the exclusions because:
* `.git` is part of our `.hgignore`, but
* `.git` is part of the `aiohttp` `tar.gz` file.
Since the file isn't needed for `pip install`-ing `aiohttp`,
and since we want `./mach vendor python` to be a no-op when there's
no requirement changes, we exclude it.
Differential Revision: https://phabricator.services.mozilla.com/D123122
fe602d7cec