Update ruby, dependencies and pin html-proofer

Author: arcivanov

.bundle/config

@@ -0,0 +1,2 @@
+---
+BUNDLE_PATH: "vendor/bundle"

.github/workflows/pybuilder.github.io.yml

@@ -10,11 +10,13 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.7
-          bundler-cache: true
+          ruby-version: "3.1"
+          bundler-cache: false
+      - name: Install Dependencies
+        run: bundle install
       - name: Build Jekyll Site
         run: $GITHUB_WORKSPACE/build.sh
       - name: Deploy Site

.gitignore

@@ -7,3 +7,4 @@ _site
 *~
 build
 Gemfile.lock
+vendor

Gemfile

@@ -1,6 +1,6 @@
 source "https://rubygems.org"
 
-gem "html-proofer"
+gem "html-proofer", "<4"
 gem "jekyll", "~> 4.0"
 gem "jekyll-sass-converter" #, "~>2.0