Upstream git tags are unreliable, replace them with commit IDs

Currently, the electron29 29.1.1-1 build cannot be reproduced because upstream appear to have deleted the v29.1.1 tag from their git repo:

https://github.com/electron/electron/tree/v29.1.1

https://web.archive.org/web/20240305112714/https://github.com/electron/electron/tree/v29.1.1 (unfortunately, the 404 - page not found and Cannot find a valid ref in v29.1.1 messages are not shown properly in the archive.org snapshot)

I recall having seen git tags "disappear" from the electron repo several times in the past, and I think this demonstrates that upstream's git tags cannot be relied upon. To mitigate this, I propose using commit IDs instead of git tags in the sources array in the electron* PKGBUILDs.