Sysroot downloader doesn't support electron 19+

[zawata]

Was experimenting with switching from our homemade native module rebuilder system to electron-rebuild when I ran into an issue:

The line of code that's failing:

rebuild/src/sysroot-fetcher.ts

Line 28 in a328ed2

const { Sha1Sum: sha, Tarball: fileName } = electronSysroots[`sid_${linuxArch}`];

fails because starting with electron 19, the sysroots are debian bullseye, not debian sid:
https://github.com/electron/electron/blob/59dd17f2cf0c816a718336d03667e42ca81ca187/script/sysroots.json

command:
npx electron-rebuild -v 21.2.2 --use-electron-clang

versions:

• Manjaro 22.0.0
• node 16.17
• electron 21.2.2
• electron-rebuild 3.2.9

[bencwallace]

Looks like this was fixed in #1046 but the version with these changes hasn't been released yet.