Fix dependabot for gomod updates

We had some issues with our multi go mod setup for the interceptor, but
this configuration might work.
We had tried to fix it with commit 68f13da
But either by mistake or some unknown reason we removed it here
#353

Author: RaphaelBut

.github/dependabot.yml

@@ -1,5 +1,13 @@
 version: 2
 updates:
+  - package-ecosystem: "gomod"
+    directories:
+      - "/"
+      - "interceptor/"
+    allow:
+      - dependency-type: all
+    schedule:
+      interval: "daily"
   - package-ecosystem: "docker"
     directory: "/build"
     labels: