`reuse download $DEPRECATED` gives unexpected result

[carmenbianca]

$ reuse download GPL-3.0                                                                                           
Error: Failed to download license. Is your internet connection working?

Oops.

Same goes for init.py.

[jeremiah]

Version 0.8.1 of reuse-tool fails when I issue this command;

reuse download --all

Instead of downloading all licenses it found it issues these messages;

Error: Failed to download license. Is your internet connection working?
Successfully downloaded LICENSES/CC-BY-4.0.txt.

Given that the second license in the message above was successfully downloaded (the CC-BY-4.0 license), perhaps the error message should be changed?

Also, digging a little more shows that the license at issue (GPL-3.0) is deprecated in SPDX v3.0 (https://spdx.org/licenses/GPL-3.0). This means that when reuse-tool went to download the GPL 3.0 license, it couldn't find it and issued the spurious message about a broken internet. I assume these issues will be solved for free when the reuse-tool moves to SPDX 3.0.