fix(ci): switch gallery-agent to sigs.k8s.io/yaml (#9397)

The gallery-agent lives under .github/, which Go tooling treats as a
hidden directory and excludes from './...' expansion. That means 'go
mod tidy' (run on every dependabot dependency bump) repeatedly strips
github.com/ghodss/yaml from go.mod/go.sum, breaking 'go run
./.github/gallery-agent' with a missing go.sum entry error.

Switch to sigs.k8s.io/yaml — API-compatible with ghodss/yaml and
already pulled in as a transitive dependency via non-hidden packages,
so tidy can no longer remove it.

.github/gallery-agent/gallery.go

@@ -7,8 +7,8 @@ import (
 	"os"
 	"strings"
 
-	"github.com/ghodss/yaml"
 	"github.com/mudler/LocalAI/core/gallery/importers"
+	"sigs.k8s.io/yaml"
 )
 
 func formatTextContent(text string) string {

.github/gallery-agent/helpers.go

@@ -9,8 +9,8 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/ghodss/yaml"
 	hfapi "github.com/mudler/LocalAI/pkg/huggingface-api"
+	"sigs.k8s.io/yaml"
 )
 
 var galleryIndexPath = os.Getenv("GALLERY_INDEX_PATH")