Set up CLA process and remove DCO (#129)

Signed-off-by: Ilan Bigio <ilan@openai.com>

.github/workflows/cla.yml

@@ -0,0 +1,29 @@
+name: CLA Assistant
+on:
+  issue_comment:
+    types: [created]
+  pull_request_target:
+    types: [opened, closed, synchronize]
+
+permissions:
+  actions: write
+  contents: write
+  pull-requests: write
+  statuses: write
+
+jobs:
+  cla:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: contributor-assistant/github-action@v2.6.1
+        if: |
+          github.event_name == 'pull_request_target' ||
+          github.event.comment.body == 'recheck' ||
+          github.event.comment.body == 'I have read the CLA Document and I hereby sign the CLA'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          path-to-document: docs/CLA.md
+          path-to-signatures: signatures/cla.json
+          branch: cla-signatures
+          allowlist: dependabot[bot]