add dependabot (#12)

Author: bgentry

.github/dependabot.yml

@@ -0,0 +1,17 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directories:
+      - "**/*"
+    groups:
+      go-dependencies:
+        update-types:
+          - "minor"
+          - "patch"
+    schedule:
+      interval: "weekly"