many: renamed module to github.com/canonical/spread-plus to fix go install for spread-plus

[ernestl]

This change should be followed up with: canonical/snapd#16813

[Copilot]

Pull request overview

This PR renames the Go module path to github.com/canonical/spread-plus so that go install works with the new repository/module location, and updates repository references accordingly.

Changes:

• Update go.mod module path to github.com/canonical/spread-plus.
• Update Go import paths and installation instructions to use the new module path.
• Update spread configuration paths/environment variables and humbox documentation/redirect URLs to point at the new repo.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
go.mod	Renames the module path to github.com/canonical/spread-plus.
cmd/spread/main.go	Updates internal import to the new module path.
cmd/humbox/main.go	Updates GitHub URL references to the new repository.
README.md	Updates go install instruction to the new module path.
spread.yaml	Updates spread project checkout path to the new module path.
tests/repack/spread.yaml	Updates GOPKG env var to the new module path for repack tests.
spread/client_test.go	Updates test import path to the new module path.
spread/openstack_test.go	Updates test import path to the new module path.
spread/project_test.go	Updates test import path to the new module path.
spread/qemu_test.go	Updates test import path to the new module path.

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[Copilot]

The redirect target uses plain HTTP. Since this is pointing to GitHub (which supports HTTPS), use an https:// URL to avoid an unnecessary downgrade/extra redirect and prevent clients from following an insecure Location header.

Suggested change

	resp.Header().Set("Location", "http://github.com/canonical/spread-plus")
	resp.Header().Set("Location", "https://github.com/canonical/spread-plus")

[Copilot]

Imports in this block are not sorted (the module import should come before github.com/niemeyer/pretty). This will be rewritten by gofmt and may fail formatting checks; please run gofmt or reorder the imports.

[maykathm]

LGTM

[ernestl]

Closing this pull request, replaced by #82.
Not allowed to use branch for fork in this repo.