Adding shebang

[Fazendaaa]

I had the same issue as reported here by me also, missing a shebang notation breaks Docker builds in Alpine based images.

[jeroen]

OK, FYI I have been building alpine images based on rhub/r-minimal and I have never had this issue, so you maybe doing something wrong. Here is one random example: https://github.com/r-universe-org/sync

But we can add the shebang if that helps.

[Fazendaaa]

Great to know, @jeroen. When I tried to build only using x86_64 as a target platform, everything runs great, this issue only happens when I use Buildx's option to cross-compile an image to ARM -- every version of ARM --, and if I'm not mistaken when I tried to compile to x86_32 the same issue happened.