Update CI (tricknotes#598)

* Update Ruby & Rails matrix
* Update Node.js version to 18
* Remove unnecessary .ruby-version
* Use HEAD of ember-cli-rails-assets for Rails 7
* Test against Rails main

See: tricknotes/ember-cli-rails-assets#17

.github/workflows/tests.yml

@@ -13,11 +13,15 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ["2.5", "2.6", "2.7", "3.0"]
-        rails: ["5.2", "6.0"]
-        exclude:
-          - ruby: "3.0"
+        ruby: ["2.7", "3.0", "3.1"]
+        rails: ["6.0", "6.1", "7.0"]
+        include:
+          - ruby: "2.7"
             rails: "5.2"
+          - ruby: "3.2"
+            rails: "7.0"
+          - ruby: "3.2"
+            rails: "main"
 
     env:
       RAILS_ENV: "test"
@@ -26,10 +30,10 @@ jobs:
     steps:
     - uses: "actions/checkout@v1"
 
-    - name: "Install NodeJS 12.x"
+    - name: "Install NodeJS 18.x"
       uses: "actions/setup-node@v1"
       with:
-        node-version: "12.x"
+        node-version: "18.x"
 
     - name: "Install Ruby ${{ matrix.ruby }}"
       uses: "ruby/setup-ruby@v1"

Gemfile

@@ -4,13 +4,14 @@ gemspec
 
 rails_version = ENV.fetch("RAILS_VERSION", "6.0")
 
-if rails_version == "master"
+if rails_version == "main"
   rails_constraint = { github: "rails/rails" }
 else
   rails_constraint = "~> #{rails_version}.0"
 end
 
 gem "rails", rails_constraint
+gem "ember-cli-rails-assets", github: "seanpdoyle/ember-cli-rails-assets" if rails_version == "main" || Gem::Version.new(rails_version) >= Gem::Version.new("7.0")
 gem "high_voltage", "~> 3.0.0"
 gem "rexml" # For selenium-webdriver on Ruby 3.0.0. This is required until selenium-webdriver 4 is released. https://github.com/SeleniumHQ/selenium/pull/9007
 gem "webdrivers", "~> 4.0"