ci: add alpha workflow (#384)

Author: Juli Ovechkina

.github/workflows/release-alpha.yml

@@ -0,0 +1,21 @@
+name: Release alpha version
+
+on:
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Extract branch name
+        shell: bash
+        run: |
+          echo "branch_name=${GITHUB_REF#refs/heads/}"
+        id: extract_branch
+      - uses: gravity-ui/release-action@v1
+        with:
+          github-token: ${{ secrets.GRAVITY_UI_BOT_GITHUB_TOKEN }}
+          npm-token: ${{ secrets.GRAVITY_UI_BOT_NPM_TOKEN }}
+          node-version: 14
+          npm-dist-tag: alpha
+          default-branch: ${{ env.branch_name }}