add .github/workflows/autorebase.yml

.github/workflows/autorebase.yml

+# File managed by web3-bot. DO NOT EDIT.
+# See https://github.com/protocol/.github/ for details.
+
+# Allow PRs opened by web3-bot to be rebased by commenting "@web3-bot rebase" on the PR.
+
+on: 
+  issue_comment:
+    types: [ created ]
+    
+name: Automatic Rebase
+jobs:
+  rebase:
+    name: Rebase
+    if: github.event.issue.pull_request != '' && github.event.issue.user.login == 'web3-bot' && contains(github.event.comment.body, '@web3-bot rebase')
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout the latest code
+      uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+        token: ${{ secrets.WEB3BOT_GITHUB_TOKEN }}
+    - name: Automatic Rebase
+      uses: cirrus-actions/rebase@7cea12ac34ab078fa37e87798d8986185afa7bf2 # v1.4
+      env:
+        GITHUB_TOKEN: ${{ secrets.WEB3BOT_GITHUB_TOKEN }}