Remove Dependabot (#3880)

We use Renovate now.

.github/dependabot.yml

@@ -1,32 +0,0 @@
-version: 2
-updates:
-  - package-ecosystem: "github-actions"
-    directory: "/"
-    schedule:
-      interval: "daily"
-      time: "11:00"
-    ignore:
-      # GitHub always delivers the latest versions for each major
-      # release tag, so handle updates manually
-      - dependency-name: "actions/*"
-      - dependency-name: "github/codeql-action/*"
-      - dependency-name: "microsoft/playwright-github-action"
-
-  - package-ecosystem: "npm"
-    directory: "/"
-    schedule:
-      interval: "daily"
-      time: "11:00"
-    ignore:
-      - dependency-name: "@types/node"
-        update-types: ["version-update:semver-major"]
-      - dependency-name: "xdg-basedir"
-        # 5.0.0 has breaking changes as they switch to named exports
-        # and convert the module to ESM
-        # We can't use it until we switch to ESM across the project
-        # See release notes: https://github.com/sindresorhus/xdg-basedir/releases/tag/v5.0.0
-        versions: ["5.x"]
-      - dependency-name: "limiter"
-        # 2.0.0 has breaking changes
-        # so we can't update yet.
-        versions: ["2.x"]