bug#39511: github tokens being deprecated

[Matt Wette]

$ guix refresh
...
Backtrace:
          12 (apply-smob/1 #<catch-closure 7f0c2c0c66c0>)
In ice-9/boot-9.scm:
    705:2 11 (call-with-prompt _ _ #<procedure default-prompt-handle?>)
In ice-9/eval.scm:
    619:8 10 (_ #(#(#<directory (guile-user) 7f0c2bd4e140>)))
In guix/ui.scm:
  1808:12  9 (run-guix-command _ . _)
In ice-9/boot-9.scm:
    829:9  8 (catch _ _ #<procedure 7f0c2bcbd3b8 at guix/ui.scm:652?> ?)
    829:9  7 (catch _ _ #<procedure 7f0c2bcbd3d0 at guix/ui.scm:775?> ?)
In guix/store.scm:
   625:10  6 (call-with-store _)
  1848:24  5 (run-with-store #<store-connection 256.99 7f0c1fd586c0> ?)
In guix/scripts/refresh.scm:
   541:14  4 (_ _)
In srfi/srfi-1.scm:
    640:9  3 (for-each #<procedure 7f0c2abf1d00 at guix/scripts/ref?> ?)
In guix/scripts/refresh.scm:
    344:2  2 (check-for-package-update #<package sbcl-stumpwm-with-?> ?)
In guix/import/github.scm:
   237:25  1 (latest-release #<package sbcl-stumpwm-with-slynk@19.11?>)
In unknown file:
           0 (scm-error misc-error #f "~A" ("Error downloading rel?") ?)

ERROR: In procedure scm-error:
Error downloading release information through the GitHub
API. This may be fixed by using an access token and setting the environment
variable GUIX_GITHUB_TOKEN, for instance one procured from
https://github.com/settings/tokens


after github token acquired:

$ guix refresh
...
guix refresh: warning: input 'Carp' of perl-xml-compile is in Perl core
gnu/packages/xml.scm:1113:13: tinyxml2 would be upgraded from 7.0.1 to 7.1.0
following redirection to 
`https://api.github.com/repositories/7715820/releases?access_token=728ec76dc9ea4344b57ba6be86674ed9e0135090'...
gnu/packages/xdisorg.scm:1731:13: python-pyperclip would be upgraded 
from 1.6.4 to 1.7.0


and then an email from github.com:

Hi @mwette,

On February 8th, 2020 at 14:37 (UTC) your personal access token (guix/bluefin) 
using GNU Guile was used as part of a query parameter to access an endpoint 
through the GitHub API:

https://api.github.com/repositories/32202720/releases

Please use the Authorization HTTP header instead, as using the `access_token` 
query parameter is deprecated and will be removed July 1st, 2020.

Depending on your API usage, we'll be sending you this email reminder once 
every 3 days for each token and User-Agent used in API calls made on your 
behalf.
Just one URL that was accessed with a token and User-Agent combination will be 
listed in the email reminder, not all.

Visithttps://developer.github.com/changes/2019-11-05-deprecated-passwords-and-authorizations-api/#authenticating-using-query-parameters
  for more information.

Thanks,
The GitHub Team