Fix infinite recursion in buildImage with default tag

[elpdt852]

Fix #131

Given that buildImage produces an OCI tarball that you can copyToRegistry as a different image ref, I don't think its worth complicating the tag to produce something input-addressed. This resolves the infinite recursion for buildImage calls without a tag defined, unfortunately I don't think it ever worked.

[graham33]

Looks like there's a check failure but makes sense

[RobbieBuxton]

Looks like there's a check failure but makes sense

I think the check error might just be an CI issue but not sure?

copying path '/nix/store/l974pi8a5yqjrjlzmg6apk0jwjv81yqw-findutils-4.9.0' from 'http://127.0.0.1:37515/'...
copying path '/nix/store/ppy5gm6r676chda5ig5xgbhr8sb3rfap-stdenv-linux' from 'http://127.0.0.1:37515/'...
building '/nix/store/z3yhs5fb3xw5pv4agbzjmw2sl441sy0b-golangci-lint.drv'...
running post-build-hook '/tmp/magic-nix-cache-build-hook-4Jltz6'...
error: unable to execute '/nix/store/vx6kg7g2xj6skg6cpqhxwsm08k6747i1-golangci-lint/bin/golangci-lint': Exec format error

I tried re-running it but it didn't help.

[elpdt852]

I've tried several things:

• Purging the GitHub action cache
• Running it locally on my NixOS laptop (it works)
• Running it on PDT's GitHub action runner (same error)

Disabling it for now. Perhaps we can fix it with a flake update to bump golangci-lint version but leaving it out of scope for this PR to unblock checks.