Installing spread via go install failed: module declares its path as github.com/snapcore/spread

Hi,

I have tried to install spread using [README](https://github.com/canonical/spread?tab=readme-ov-file#install):
```
go install github.com/canonical/spread/cmd/spread@latest
```

Steps-to-reproduce:
```
lxc launch --vm ubuntu:24.04 -c limits.cpu=4 -c limits.memory=8GB -d root,size=50GiB testx
lxc exec testx bash

snap install go --classic
PATH=$PATH:$HOME/go/bin/
go install github.com/canonical/spread/cmd/spread@latest
```

Actual results:
```
root@testx:~# go install github.com/canonical/spread/cmd/spread@latest
go: downloading github.com/canonical/spread v0.0.0-20250604131136-ae284792596e
go: github.com/canonical/spread/cmd/spread@latest: version constraints conflict:
github.com/canonical/spread@v0.0.0-20250604131136-ae284792596e: parsing go.mod:
module declares its path as: github.com/snapcore/spread
but was required as: github.com/canonical/spread
```

Expected results: successful installation.

Note, following the 'go' advice helps:
```
root@testx:~# go install github.com/snapcore/spread/cmd/spread@latest
go: downloading github.com/snapcore/spread v0.0.0-20250604131136-ae284792596e
go: downloading github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e
go: downloading github.com/go-goose/goose/v5 v5.0.0-20230421180421-abaee9096e3a
go: downloading golang.org/x/crypto v0.36.0
go: downloading golang.org/x/net v0.38.0
go: downloading golang.org/x/oauth2 v0.25.0
go: downloading golang.org/x/term v0.30.0
go: downloading gopkg.in/tomb.v2 v2.0.0-20161208151619-d5d1b5820637
go: downloading gopkg.in/yaml.v2 v2.4.0
go: downloading github.com/kr/text v0.2.0
go: downloading github.com/juju/collections v0.0.0-20220203020748-febd7cad8a7a
go: downloading cloud.google.com/go/compute/metadata v0.3.0
go: downloading golang.org/x/sys v0.31.0

root@testx:~# spread --help
Usage of spread:
...
```

Consider to update [go.mod](https://github.com/canonical/spread/blob/ae284792596e00d325a1787604fe4ec7e00574aa/go.mod#L1). Tnx!

P.S. it is fresh regression from https://github.com/canonical/spread/pull/238 CC: @nicolasbock