Hello,

I have encounter a issue with "guix import pypi" :

```

guix import: warning: Failed to extract file: PyPortfolioOpt-1.5.1.dist-info/METADATA from wheel.
guix import: warning: Cannot guess requirements from source archive: no requires.txt file found.

```

## reproduce the bug

```

(base) guix import pypi  PyPortfolioOpt
following redirection to `https://pypi.org/pypi/pyportfolioopt/json'...

Starting download of /tmp/guix-file.mwZdLg
From https://files.pythonhosted.org/packages/97/c2/c7569f2773f3e942367e90dcca15a235af3d3330ac8abfcbfbe67a8ba8dd/PyPortfolioOpt-1.5.1.tar.gz...
 …t-1.5.1.tar.gz  56KiB               2.7MiB/s 00:00 [##################] 100.0%

Starting download of /tmp/guix-file.mHBgak
From https://files.pythonhosted.org/packages/90/98/3906835b783ba39cfc613c7b0c0fde9c758c729ff3406d45f1c2a1116961/PyPortfolioOpt-1.5.1-py3-none-any.whl...
 ….1-py3-none-any.whl  60KiB          2.1MiB/s 00:00 [##################] 100.0%
guix import: warning: Failed to extract file: PyPortfolioOpt-1.5.1.dist-info/METADATA from wheel.
guix import: warning: Cannot guess requirements from source archive: no requires.txt file found.
(package
  (name "python-pyportfolioopt")
  (version "1.5.1")
  (source
    (origin
      (method url-fetch)
      (uri (pypi-uri "pyportfolioopt" version))
      (sha256
        (base32 "162d6jyvba0xk2blssbp52rrjqpjv011h988k150p1fg7x7nzbs9"))))
  (build-system python-build-system)
  (home-page "https://github.com/robertmartin8/PyPortfolioOpt")
  (synopsis "Financial portfolio optimization in python")
  (description "Financial portfolio optimization in python")
  (license license:expat))
(base) guix describe
Generation 220 Dec 27 2021 12:01:04 (current)
  guix 9bbbac6
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 9bbbac6783bcdace17d967e85c8ae8d14cbf1ef9

```

## additional information

This user has encountered a similar issue for "guix import pypi httpie"

However "guix import pypi httpie" runs for my version of guix.