Gitlab add groups support

[askripe]

No description provided.

[Copilot]

Pull request overview

Adds GitLab group CI/CD variable support to the existing GitLab provider by extending the reference path format and updating the documentation accordingly.

Changes:

• Add buildURL helper to support host/groups/<id>/<var> in addition to legacy project references.
• Update GitLab provider docs in README.md with group/project examples and an expanded syntax description.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
pkg/providers/gitlab/gitlab.go	Adds URL construction logic that dispatches between projects vs groups based on the key path format.
README.md	Documents the new GitLab reference formats and provides examples for project and group variables.

Comments suppressed due to low confidence (1)

pkg/providers/gitlab/gitlab.go:102

• ssl_verify handling is inverted for tls.Config.InsecureSkipVerify: when ssl_verify=true (the default), this currently sets InsecureSkipVerify to true, which disables certificate verification. Flip the boolean (or rename the config/field) so that ssl_verify=false is the only case that skips verification.

	tr := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: p.SSLVerify},
	}

[yxxhero]

@askripe please fix DCO issue