Upgrade dependencies

pip-compile -U

Mainly to ensure the latest version of Babel is installed – when I was
working with the toolforge_i18n commit pulled in by the previous commit
(mapping more language codes to Babel equivalents), I found that the
Babel in my lexeme-forms venv somehow had fewer locale-data files than
the Babel in my wd-image-positions venv (despite both ostensibly being
the same version), so I want to make sure a very recent Babel is
installed everywhere I use this tool. (I have no idea what actually
happened there – did they push multiple versions of Babel 2.14.0 with
the same Python code but different locale-data files to PyPI? – but
hopefully this helps, and it generally doesn’t hurt anyway.)