[release-0.10] - Adds dependency on github.com/grafana/jsonnet-libs mixins-util (#2480)

* Add lockfile

* chore: ignore mdox errors for https://www.weave.works

* ci: Generate with newer go version

jsonnetfile.json

@@ -1,6 +1,15 @@
 {
   "version": 1,
   "dependencies": [
+    {
+      "source": {
+        "git": {
+          "remote": "https://github.com/grafana/jsonnet-libs.git",
+          "subdir": "mixin-utils"
+        }
+      },
+      "version": "master"
+    },
     {
       "source": {
         "local": {