Configure dependabot for several ecosystems

.github/Dockerfile

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+# Dummy Dockerfile for dependabot, if it finds an update we need to update docker-compose.yml
+#
+FROM nginx:1.25.0

.github/dependabot.yml

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+version: 2
+
+updates:
+  - package-ecosystem: "docker"
+    directory: "/"
+    open-pull-requests-limit: 1
+    schedule:
+      interval: "daily"
+    #  interval: "weekly"
+    #  day: "wednesday"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    open-pull-requests-limit: 1
+    schedule:
+      interval: "daily"
+    #  interval: monthly
+  - package-ecosystem: "gomod"
+    directory: "/"
+    open-pull-requests-limit: 1
+    schedule:
+      interval: "daily"
+    #  interval: "weekly"
+    #  day: "wednesday"