That's pretty big, because it includes these modules' `.git` and `.tox`,
which sums to gigabytes.

swh-web depends on swh-indexer so we must ensure swh-indexer is installed
first (otherwise the last pubished version is used instead of the one
from the sources).

and add swh-storage[listener] dep for the sake of completeness while
building the doc.

that builds the doc using source code repos located one directory above
instead of published versions of swh subpackages.

Related to T1330.