Add GitHub action to automatically update download zip

.github/workflows/deploy.yml

@@ -0,0 +1,34 @@
+name: deploy
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+      - master
+    paths:
+      - 'README.rdoc'
+      - 'src/**/*'
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write
+    steps:
+      - uses: actions/create-github-app-token@v3
+        id: koans-deploy-app-token
+        with:
+          client-id: ${{ vars.DEPLOY_APP_CLIENT_ID }}
+          private-key: ${{ secrets.DEPLOY_APP_SECRET_KEY }}
+          owner: edgecase
+          repositories: ruby_koans
+          permission-contents: write
+      - uses: actions/checkout@v7
+        with:
+          token: ${{ steps.koans-deploy-app-token.outputs.token }}
+      - run: 'rake package'
+      - run: |-
+          git config --global user.name 'GitHub Actions'
+          git config --global user.email '41898282+github-actions[bot]@users.noreply.github.com'
+          git add download/
+          git commit -m 'Update download .zip file [skip ci]' || true
+          git push

DEPLOYING

@@ -1,12 +1,15 @@
 = Deploying a new Ruby Koans ZIP file
 
 The "Download" button on the rubykoans.com web-site points to the
-download/rubykoans.zip file in the github repository. So to update the
-download target on the web-site, just rebuild the .zip file, commit
-and push the changes.
+download/rubykoans.zip file in the GitHub repository. That file is
+automatically updated by GitHub Actions when the source files are
+updated.
+
+It can, of course, also be updated manually. To do so, just rebuild
+the .zip file, commit, and push the changes.
 
     rake package
     git add download
     git push
 
-That's it.
+That's it.

Rakefile

@@ -92,18 +92,13 @@ task :clobber_zip do
   rm ZIP_FILE
 end
 
-file ZIP_FILE => KOAN_FILES + [DOWNLOAD_DIR] do
+file ZIP_FILE => [:gen, DOWNLOAD_DIR] do
   sh "zip #{ZIP_FILE} #{PROB_DIR}/*"
 end
 
 desc "Create packaged files for distribution"
 task :package => [ZIP_FILE]
 
-desc "Upload the package files to the web server"
-task :upload => [ZIP_FILE] do
-  sh "scp #{ZIP_FILE} linode:sites/onestepback.org/download"
-end
-
 desc "Generate the Koans from the source files from scratch."
 task :regen => [:clobber_koans, :gen]