Moving Site Deployment script to GHA

Author: osalpekar

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: Unit-tests on Linux CPU
+
+on:
+  pull_request:
+  push:
+    branches:
+      - site
+  workflow_dispatch:
+
+jobs:
+  tests:
+    uses: pytorch/test-infra/.github/workflows/linux_job.yml@main
+    with:
+      runner: linux.12xlarge
+      repository: pytorch/pytorch.github.io
+      docker-image: cimg/ruby:2.7-node
+      script: |
+        git config --global --add safe.directory /__w/pytorch.github.io/pytorch.github.io
+        set -euxo pipefail
+
+        ## Bundle Install
+        bundle config set --local path 'vendor/bundle'
+        bundle install
+
+        ## Yarn Install
+        yarn install --cache-folder ~/.cache/yarn
+
+        ## Notedown Install
+        sudo apt update && sudo apt install python3-pip && sudo -H pip3 install pyrsistent==0.16 notedown pyyaml -Iv nbformat==5.7
+
+        ## Configure Bot
+        git config --global user.email "facebook-circleci-bot@users.noreply.github.com"
+        git config --global user.name "Website Deployment Script"
+
+        ## Build Jekyll site and push to master
+        ./scripts/deploy-site.sh build