ci: Create dependabot (#728)

* Create dependabot

Create dependabot file.

* add changelog entry

.github/dependabot.yml

@@ -0,0 +1,11 @@
+# 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" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"

CHANGELOG.md

@@ -50,7 +50,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * [#715](https://github.com/NibiruChain/nibiru/pull/715) - remove redundant perp.Keeper.SetPosition parameters
 * [#718](https://github.com/NibiruChain/nibiru/pull/718) - add guard clauses on OpenPosition (leverage and quote amount != 0)
-* [#723](https://github.com/NibiruChain/nibiru/pull/723) - refactor perp keeper's `RemoveMargin` method
+* [#728](https://github.com/NibiruChain/nibiru/pull/728) - add dependabot file into the project.
+- [#723](https://github.com/NibiruChain/nibiru/pull/723) - refactor perp keeper's `RemoveMargin` method
 * [#730](https://github.com/NibiruChain/nibiru/pull/730) - update localnet script.
 
 ### API Breaking