Add dependabot configuration.

For more information, see:

https://docs.github.com/en/code-security/supply-chain-security/keeping-your-dependencies-updated-automatically

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: gomod
+    directory: /
+    schedule:
+      interval: daily