feat: add fake tag (#770)

.github/workflows/fake-tag.yml

+name: fake tag
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "python/sglang/version.py"
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+jobs:
+  publish:
+    if: github.repository == 'sgl-project/sglang'
+    runs-on: ubuntu-latest
+    environment: 'prod'
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Get version
+        id: get_version
+        run: |
+          version=$(cat python/sglang/version.py | cut -d'"' -f2)
+          echo "TAG=v$version" >> $GITHUB_OUTPUT
+
+      - name: Create and push fake tag
+        env:
+          GITHUB_TOKEN: ${{ secrets.REPO_TOKEN }}
+        run: |
+          git config user.name zhyncs
+          git config user.email me@zhyncs.com
+          git checkout -b ${{ steps.get_version.outputs.TAG }}
+          git push --set-upstream origin ${{ steps.get_version.outputs.TAG }}