automate add reviewers

.github/reviewers.yml

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+# see https://github.com/marketplace/actions/auto-request-review
+reviewers:
+  # The default reviewers
+  defaults:
+    -  # mwmerz
+
+options:
+  ignore_draft: true
+  ignored_keywords:
+    - DO NOT REVIEW
+  enable_group_assignment: false
+
+  # Randomly pick reviewers up to this number.
+  # Do not set this option if you'd like to assign all matching reviewers.
+  number_of_reviewers: 3
+
+  # If it's true, the last matching files-change pattern takes the most precedence (CODEOWNERS-compatible)
+  # See https://github.com/necojackarc/auto-request-review/pull/80 for more details.
+  last_files_match_only: false

.github/workflows/add-reviewers.yml

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+name: Auto Request Review
+
+on:
+  pull_request:
+    types: [opened, ready_for_review, reopened]
+
+jobs:
+  auto-request-review:
+    name: Auto Request Review
+    runs-on: ubuntu-latest
+    steps:
+      - name: Request review based on files changes and/or groups the author belongs to
+        uses: necojackarc/auto-request-review@v0.12.0
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          config: .github/reviewers.yml # Config file location override
+          # Look for config locally during run instead of in repo.
+          # For instance, if you'd like to use a config file stored in external storage,
+          # you can fetch it before you run this action, then let this action pick it up with `use_local: true`.
+          # This defaults to false if not specified.
+          # See https://github.com/necojackarc/auto-request-review/issues/76 for more details.
+          use_local: true