Initial dependabot setup (#30)

Author: fabito

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  # Configuration for Dockerfile
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    commit-message:
+      # Prefix all commit messages with "[docker] " (no colon, but a trailing whitespace)
+      prefix: "[docker] "