Add a way to specify github token for downloading binaries, can pass workflow generated token

[kirillbilchenko]

Add a way to specify github token for downloading binaries, can pass workflow generated token

[jtyr]

Thanks for your PR, @kirillbilchenko. May I ask you why do you need to pass a GH token to download files from a public repo?

[kirillbilchenko]

This one is useful if you are having nat, and for example multiple apps working with github api, so you will not rate limit for non auth calls.

[jtyr]

I see. What about to put something like this above the if [ $DOWNLOADER = 'curl' ]; then:

if [ -z "${GITHUB_TOKEN}" ]; then
  header="--header='Authorization: Bearer ${GITHUB_TOKEN}'"
fi

And then in each of the command just add it like this:

DOWNLOAD_URL=$(curl -sL "$header" "$latest_url" | grep "$OS-$ARCH" | awk '/"browser_download_url":/{gsub(/[,"]/,"", $2); print $2}' 2>/dev/null)
PROJECT_CHECKSUM=$(curl -sL "$header" "$latest_url" | grep "$PROJECT_CHECKSUM_FILE" | awk '/"browser_download_url":/{gsub(/[,"]/,"", $2); print $2}' 2>/dev/null)

That should help to reduce the code redundancy a little bit.