chore: upgrade to GitHub-native dependabot (hexojs#4689)

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

.github/dependabot.yml

@@ -0,0 +1,16 @@
+version: 2
+updates:
+- package-ecosystem: npm
+ directory: "/"
+ schedule:
+ interval: daily
+ open-pull-requests-limit: 20
+ ignore:
+ - dependency-name: husky
+ versions:
+ - 5.0.9
+ - 5.1.0
+ - 5.1.1
+ - 5.1.2
+ - 5.1.3
+ - 5.2.0