chore(ci, cd): build and deploy via _gh-actions_ directly

New actions available in GitHub allow for building and deploying the site
completely from the actions workflow with minimal code.
The deploy.sh script is no longer necessary with these changes.

tools/test.sh

@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+#
+# Build and test the site content
+#
+# Requirement: html-proofer, jekyll
+#
+# Usage: See help information
+
+set -eu
+
+SITE_DIR="_site"
+
+_config="_config.yml"
+
+help() {
+  echo "Build and test the site content"
+  echo
+  echo "Usage:"
+  echo
+  echo "   bash ./tools/test.sh [options]"
+  echo
+  echo "Options:"
+  echo '     -c, --config   "<config_a[,config_b[...]]>"    Specify config file(s)'
+  echo "     -h, --help               Print this information."
+}
+
+main() {
+  # clean up
+  if [[ -d $SITE_DIR ]]; then
+    rm -rf "$SITE_DIR"
+  fi
+
+  _baseurl="$(grep '^baseurl:' "$_config" | sed "s/.*: *//;s/['\"]//g;s/#.*//")"
+
+  # build
+  JEKYLL_ENV=production bundle exec jekyll build \
+    --destination "$SITE_DIR$_baseurl" \
+    --config "$_config"
+
+  # test
+  bundle exec htmlproofer "$SITE_DIR" \
+    --disable-external \
+    --check-html \
+    --allow_hash_href
+}
+
+while (($#)); do
+  opt="$1"
+  case $opt in
+  -c | --config)
+    _config="$2"
+    shift
+    shift
+    ;;
+  -h | --help)
+    help
+    exit 0
+    ;;
+  *)
+    # unknown option
+    help
+    exit 1
+    ;;
+  esac
+done
+
+main