pr-upload: Fix a typo affecting Internet Archive

[sjackman]

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Fix a typo in pr-upload affecting Internet Archive. Not sure how this typo slipped in. Sigh

[BrewTestBot]

Review period will end on 2021-02-25 at 23:08:51 UTC.

[BrewTestBot]

Review period skipped due to critical label.

[sjackman]

CI / test everything (macOS) (pull_request)

  brew audit --skip-style
audit for lg-onscreen-control: failed
 - cannot use the sha256 for an empty string: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
 - Cask should have a description. Please add a `desc` stanza.

https://github.com/Homebrew/brew/pull/10697/checks?check_run_id=1974574815#step:12:8
😕

[Bo98]

https://github.com/Homebrew/homebrew-cask-drivers/pull/2056