Bug with UCD data "BadZipFile" on first run

It only happens when running the first time, then when running again it's fine, so maybe some timing issue, not waiting until the end of some download? And not blocking, since it's enough to restart the run. Here is the stacktrace:

```
[4/5] _diffenator "build/Font/variable/old-Font-Italic.ttf" "bui...um Italic-Text Bold Italic/Text-Bold-Italic' -ch ".*" --coords axes=...
FAILED: out/Bold Italic-Italic-Medium Italic-Text Bold Italic/Text-Bold-Italic
_diffenator "build/Font/variable/old-Font-Italic.ttf" "build/Font/variable/Font-Italic.ttf" -t 0.9 -o 'out/Bold Italic-Italic-Medium Italic-Text Bold Italic/Text-Bold-Italic' -ch ".*" --coords axes=...
Traceback (most recent call last):
File "/home/jany_belluz/.local/bin/_diffenator", line 8, in
sys.exit(main())
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/diffenator2/_diffenator.py", line 83, in main
diff.diff_all()
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/diffenator2/_diffenator.py", line 30, in diff_all
getattr(self,f)()
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/diffenator2/_diffenator.py", line 39, in diff_words
self.glyph_diff = test_fonts(self.old_font, self.new_font, threshold=self.threshold)
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/diffenator2/shape.py", line 53, in test_fonts
words = test_font_words(font_a, font_b, skip_glyphs, threshold=threshold)
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/diffenator2/shape.py", line 87, in test_font_words
data = ucd_data(k)
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/youseedee/__init__.py", line 176, in ucd_data
out.update(props["datareader"](file, codepoint))
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/youseedee/__init__.py", line 73, in dictget
fileentry["data"] = fileentry["reader"](filename)
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/youseedee/__init__.py", line 58, in parse_file_semicolonsep
ensure_files()
File "/home/jany_belluz/.local/pipx/venvs/diffenator2/lib/python3.10/site-packages/youseedee/__init__.py", line 40, in ensure_files
with zipfile.ZipFile(zip_path, 'r') as zip_ref:
File "/usr/lib/python3.10/zipfile.py", line 1269, in __init__
self._RealGetContents()
File "/usr/lib/python3.10/zipfile.py", line 1336, in _RealGetContents
raise BadZipFile("File is not a zip file")
zipfile.BadZipFile: File is not a zip file
```