Fixes https://github.com/coder/coder/issues/17063
I'm ignoring flake.nix for now.
```
$ IGNORE_NIX=true ./scripts/check_go_versions.sh
INFO : go.mod : 1.24.1
INFO : dogfood/coder/Dockerfile : 1.24.1
INFO : setup-go/action.yaml : 1.24.1
INFO : flake.nix : 1.22
INFO : Ignoring flake.nix, as IGNORE_NIX=true
Go version check passed, all versions are 1.24.1
$ ./scripts/check_go_versions.sh
INFO : go.mod : 1.24.1
INFO : dogfood/coder/Dockerfile : 1.24.1
INFO : setup-go/action.yaml : 1.24.1
INFO : flake.nix : 1.22
ERROR: Go version mismatch between go.mod and flake.nix
```