translate-toolkit version 3.13.0-2 ftbfs

[Pushkar Kulkarni]

Build-time tests seem to fail [1] due to:

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E ModuleNotFoundError: No module named 'charset_normalizer'

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I see that `python3-charset-normalizer` is not a build dependency in debian/control.

The build still passes in a debian/sid chroot because python3-charset-normalizer is pulled in as a transitive dependency (most likely for python3-requests). See [2].

For now, I believe we must add `python3-charset-normalizer` as a builddep.

[1] https://launchpadlibrarian.net/736233592/buildlog_ubuntu-oracular-amd64.translate-toolkit_3.13.0-2_BUILDING.txt.gz
[2] https://paste.ubuntu.com/p/dVHbpvW8fj/