Merge pull request #480 from prometheus/superq/update_sigv4-bot

Enable dependabot for sigv4

Author: Julien Pivotto

.github/dependabot.yml

@@ -4,3 +4,7 @@ updates:
     directory: "/"
     schedule:
       interval: monthly
+  - package-ecosystem: "gomod"
+    directory: "/sigv4"
+    schedule:
+      interval: monthly