Milestone A: modernize GitHub Actions (checkout v4, ruby/setup-ruby)

Author: Jason Hill

.github/workflows/ci.yml

@@ -5,7 +5,7 @@ jobs:
   static_analysis:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v4
     - uses: workarea-commerce/ci/bundler-audit@v1
     - uses: workarea-commerce/ci/rubocop@v1
     - uses: workarea-commerce/ci/eslint@v1
@@ -18,43 +18,47 @@ jobs:
   admin_tests:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - uses: actions/setup-ruby@v1
+    - uses: actions/checkout@v4
+    - uses: ruby/setup-ruby@v1
       with:
         ruby-version: 2.6.x
+        bundler-cache: true
     - uses: workarea-commerce/ci/test@v1
       with:
         command: bin/rails app:workarea:test:admin
 
   core_tests:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - uses: actions/setup-ruby@v1
+    - uses: actions/checkout@v4
+    - uses: ruby/setup-ruby@v1
       with:
         ruby-version: 2.6.x
+        bundler-cache: true
     - uses: workarea-commerce/ci/test@v1
       with:
         command: bin/rails app:workarea:test:core
 
   storefront_tests:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - uses: actions/setup-ruby@v1
+    - uses: actions/checkout@v4
+    - uses: ruby/setup-ruby@v1
       with:
         ruby-version: 2.6.x
+        bundler-cache: true
     - uses: workarea-commerce/ci/test@v1
       with:
         command: bin/rails app:workarea:test:storefront
 
   plugins_tests:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - uses: actions/setup-ruby@v1
+    - uses: actions/checkout@v4
+    - uses: ruby/setup-ruby@v1
       with:
         ruby-version: 2.6.x
+        bundler-cache: true
     - uses: workarea-commerce/ci/test@v1
       with:
         command: bin/rails app:workarea:test:plugins