Fix dependabot.yml syntax error

(cherry picked from commit 5da67ac)

Author: jiridanek

.github/dependabot.yml

@@ -31,7 +31,7 @@ updates:
     schedule:
       interval: "daily"
   - package-ecosystem: "docker"
-    labels: "image"
+    labels: ["image"]
     directory: "/"
     schedule:
       interval: "daily"