chore: re-sync bootstrap script from GH

From latest in github/scriptstorulethemall

script/bootstrap

@@ -1,10 +1,31 @@
 #!/bin/sh
 
+# script/bootstrap: Resolve all dependencies that the application requires to
+#                   run.
+
 set -e
-export PATH=/usr/share/rbenv/shims:$PATH RBENV_VERSION=$(cat .ruby-version)
 
-script/branding
+cd "$(dirname "$0")/.."
+
+if [ -f "Brewfile" ] && [ "$(uname -s)" = "Darwin" ]; then
+  brew bundle check >/dev/null 2>&1  || {
+    echo "==> Installing Homebrew dependencies…"
+    brew bundle
+  }
+fi
+
+if [ -f ".ruby-version" ] && [ -z "$(rbenv version-name 2>/dev/null)" ]; then
+  echo "==> Installing Ruby…"
+  rbenv install --skip-existing
+  which bundle >/dev/null 2>&1  || {
+    gem install bundler
+    rbenv rehash
+  }
+fi
 
-echo "Let's get set up here..."
-bundle install
-echo "Boom."
+if [ -f "Gemfile" ]; then
+  echo "==> Installing gem dependencies…"
+  bundle check --path vendor/gems >/dev/null 2>&1  || {
+    bundle install --path vendor/gems --quiet --without production
+  }
+fi