chore: upgrade to GitHub-native dependabot (#85)

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

.github/dependabot.yml

@@ -0,0 +1,22 @@
+version: 2
+updates:
+- package-ecosystem: npm
+  directory: "/"
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 20
+  ignore:
+  - dependency-name: eslint
+    versions:
+    - 7.18.0
+    - 7.19.0
+    - 7.20.0
+    - 7.21.0
+    - 7.22.0
+    - 7.23.0
+    - 7.24.0
+  - dependency-name: mocha
+    versions:
+    - 8.2.1
+    - 8.3.0
+    - 8.3.1