[BUG] version check SEGV in toolexec mode on go 1.23

[eliottness]

Version of orchestrion

Latest & main

Describe what happened:

The call tools/packages.Load will return with no errors with pkg.Module being nil. This being not checked create this error:

❯ go test -v -tags=integration,buildtag -shuffle=on -toolexec "$PWD/../orchestrion toolexec" ./tests/redigo
# github.com/docker/docker/errdefs
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0xdeaed6]

goroutine 1 [running]:
github.com/DataDog/orchestrion/internal/ensure.goModVersion({0x0?, 0xc00023bc38?})
        /home/eliott/dd/orchestrion/internal/ensure/requiredversion.go:150 +0x116
github.com/DataDog/orchestrion/internal/ensure.requiredVersion(0x10fb8bf?, 0x11548e0, 0x1155108, {0xc0001b8000, 0xe, 0xe})
        /home/eliott/dd/orchestrion/internal/ensure/requiredversion.go:66 +0x6a
github.com/DataDog/orchestrion/internal/ensure.RequiredVersion(...)
        /home/eliott/dd/orchestrion/internal/ensure/requiredversion.go:44
github.com/DataDog/orchestrion/internal/pin.init.0()
        /home/eliott/dd/orchestrion/internal/pin/pin.go:146 +0x68

Describe what you expected:

I guess we expect orchestrion execution to not happen in this case because we have no way to make sure we are running the right version of orchestrion.

Steps to reproduce the issue:

This issue only happen on certain conditions:

• Need at least go 1.23
• Need to use orchestrion in TOOLEXEC mode (meaning with -toolexec, not with orchestrion go ...)
• Only some packages of the github.com/docker/docker repository are reproductiing this issue

Then running any integration test trying to build github.com/docker/docker reproduce the issue

[eliottness]

Ok so for some reasons, on certain builds, the go toolchain is calling go tool vet. And since the version check happen in an init function, it runs before we are able bail out. So we only have to NOT crash and return an error in the version check code and nothing more should be happening