*: add bazeldnf dependency

This adds https://github.com/rmohr/bazeldnf, a pure-Go RPM dependency
resolver. Requires a dummy import for proper Go dependency resolution.

Change-Id: I4d4e7716bfd7da7e3157f06dc1f1612c9e39c17e
Reviewed-on: https://review.monogon.dev/c/monogon/+/1028
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Leopold Schabel <leo@monogon.tech>
diff --git a/third_party/sandboxroot/tools.go b/third_party/sandboxroot/tools.go
new file mode 100644
index 0000000..578e592
--- /dev/null
+++ b/third_party/sandboxroot/tools.go
@@ -0,0 +1,8 @@
+//go:build tools
+// +build tools
+
+package sandboxroot
+
+import (
+	_ "github.com/rmohr/bazeldnf/cmd"
+)