Force gazelle to use third_party gazelle dep (#68)

#61 attempted
to do this, but running gazelle undoes it - instead, tell gazelle to
keep preserving this property.

BUILD.bazel

@@ -1,5 +1,7 @@
 load("@bazel_gazelle//:def.bzl", "gazelle")
 
+# gazelle:resolve go github.com/bazelbuild/bazel-gazelle/label @com_github_bazelbuild_bazel_gazelle//label
+
 # gazelle:prefix github.com/bazel-contrib/target-determinator
 gazelle(
     name = "gazelle",

scripts/format

@@ -9,3 +9,5 @@ echo "importsort" >&2
 find $(pwd) -type f -name '*.go' |
     grep -v ".pb.go" |
     xargs bazel run --noshow_progress --ui_event_filters= @com_github_aristanetworks_goarista//cmd/importsort -- -w -s NOT_SPECIFIED
+
+bazel run //:gazelle