Usage with ELECTRON_MIRROR produces incorrect download URL

[prince-chrismc]

Running with

leads to

Notice the "middle URL" is 12.0.9 however the link on GitHub is https://github.com/electron/electron/releases/download/v12.0.9/electron-v12.0.9-win32-x64.zip

Notice the v12.0.9

Change my ENV to

Allows app-builder build to successfully download the runtimes and output an application

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I see it's added https://github.com/develar/app-builder/blob/c79345743b794ccef41493decafb0b5b2eece505/pkg/electron/electronDownloader.go#L100

I suspect https://github.com/develar/app-builder/blob/c79345743b794ccef41493decafb0b5b2eece505/pkg/electron/electronDownloader.go#L91 should gain the same

This change would make it consistent with electron/get which adds the v prefix https://github.com/electron/get/blob/a7ed0a066eb81cb1eaa86942db12e6ed48155f98/src/utils.ts#L32