Create auto-approve.yml (#138)

* Create auto-approve.yml

* Create autoupdate.yml

.github/workflows/auto-approve.yml

+name: Auto approve
+
+on:
+  pull_request_target
+
+jobs:
+  auto-approve:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: hmarr/auto-approve-action@v2.1.0
+        if: github.actor == 'scala-steward' || github.actor == 'renovate[bot]'
+        with:
+          github-token: "${{ secrets.GITHUB_TOKEN }}"

.github/workflows/autoupdate.yml

+name: autoupdate
+on:
+  push: {}
+jobs:
+  autoupdate:
+    name: autoupdate
+    runs-on: ubuntu-latest
+    steps:
+      - uses: docker://chinthakagodawita/autoupdate-action:v1
+        env:
+          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
+          PR_FILTER: "labelled"
+          PR_LABELS: "type: dependencies,autoupdate"
+          EXCLUDED_LABELS: "do-not-autoupdate"