Change dependabot schedules to monthly (#414)

Author: stchris

.github/dependabot.yml

@@ -3,14 +3,12 @@ updates:
 - package-ecosystem: docker
   directory: "/"
   schedule:
-    interval: daily
-    time: "01:00"
+    interval: monthly
   open-pull-requests-limit: 99
 - package-ecosystem: pip
   directory: "/"
   schedule:
-    interval: daily
-    time: "01:00"
+    interval: monthly
   open-pull-requests-limit: 99
   ignore:
   - dependency-name: followthemoney