ci: add pr-add-label workflow (doocs#1605)

* ci: add pr-add-label workflow

* fix: use master

* chore: change job name

Author: thinkasany

.github/workflows/pr-add-label.yml

@@ -0,0 +1,22 @@
+name: pr-add-label
+
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+jobs:
+  add-label:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check PR number
+        id: pr_number
+        run: echo "PR_NUMBER=${{ github.event.pull_request.number }}" >> $GITHUB_ENV
+
+      - name: Run add-label Action
+        uses: thinkasany/pr-label-action@master
+        with:
+          github_token: ${{ secrets.DOOCS_BOT_ACTION_TOKEN }}
+          pr_number: ${{ env.PR_NUMBER }}
+          organize_name: "doocs"
+          team_name: "leetcode-algorithm"