refactor: mark pkg/strings as deprecated in favor of stdlib

pkg/strings/strings.go

@@ -1,10 +1,9 @@
 package strings
 
+import "slices"
+
+// Deprecated: Use go slices package instead.
 func Contains(list []string, needle string) bool {
-	for _, item := range list {
-		if item == needle {
-			return true
-		}
-	}
-	return false
+	// TODO(v4): remove package.
+	return slices.Contains(list, needle)
 }