func (s *ReleasesService) GetRelease(pid interface{}, tagName string, options ...RequestOptionFunc) (*Release, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/releases/%s", pathEscape(project), pathEscape(tagName))
	req, err := s.client.NewRequest(http.MethodGet, u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	r := new(Release)
	resp, err := s.client.Do(req, r)
	if err != nil {
		return nil, resp, err
	}
	return r, resp, err
}
GetRelease returns a single release, identified by a tag name.

GitLab API docs:
https://docs.gitlab.com/ce/api/releases/index.html#get-a-release-by-a-tag-name
package gitlab
import (
	"fmt"
	"net/http"
	"time"
)
type ReleasesService struct {
	client *Client
}
type Release struct {
	TagName         string     `json:"tag_name"`
	Name            string     `json:"name"`
	Description     string     `json:"description"`
	DescriptionHTML string     `json:"description_html"`
	CreatedAt       *time.Time `json:"created_at"`
	ReleasedAt      *time.Time `json:"released_at"`
	Author          struct {
		ID        int    `json:"id"`
		Name      string `json:"name"`
		Username  string `json:"username"`
		State     string `json:"state"`
		AvatarURL string `json:"avatar_url"`
		WebURL    string `json:"web_url"`
	} `json:"author"`
	Commit Commit `json:"commit"`
	Assets struct {
		Count   int `json:"count"`
		Sources []struct {
			Format string `json:"format"`
			URL    string `json:"url"`
		} `json:"sources"`
		Links []*ReleaseLink `json:"links"`
	} `json:"assets"`
}
type ListReleasesOptions ListOptions
func (s *ReleasesService) ListReleases(pid interface{}, opt *ListReleasesOptions, options ...RequestOptionFunc) ([]*Release, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/releases", pathEscape(project))
	req, err := s.client.NewRequest(http.MethodGet, u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	var rs []*Release
	resp, err := s.client.Do(req, &rs)
	if err != nil {
		return nil, resp, err
	}
	return rs, resp, err
}