CI: Update Matrix and bump local Ruby version (#35)

Update Ruby Matrix to include supported, stable releases of Ruby, as
well as Rails `v7.1`. Drops support for Rails `v6.0`.

Updates local version of Ruby to the latest stable version, which at the
time of this writing is `3.3.4`.

Pins `sqlite3` to `~> 1.4` to avoid the following error when running
`bin/setup`:

```
Error loading the 'sqlite3' Active Record adapter
```

This is because Rails [supports][] only that version

[supports]: https://github.com/rails/rails/blob/v7.1.3.4/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb#L14

.github/workflows/ci.yml

@@ -7,14 +7,18 @@ jobs:
  fail-fast: false
  matrix:
  ruby-version:
- - "2.7"
  - "3.0"
  - "3.1"
+ - "3.2"
+ - "3.3"
  rails-version:
- - "7.0"
  - "6.1"
- - "6.0"
+ - "7.0"
+ - "7.1"
  - "main"
+ exclude:
+ - ruby-version: "3.0"
+ rails-version: "main"
 
  env:
  RAILS_VERSION: ${{ matrix.rails-version }}
@@ -25,7 +29,7 @@ jobs:
  steps:
  - uses: actions/checkout@v3
  - name: Set up Ruby
- uses: ruby/setup-ruby@359bebbc29cbe6c87da6bc9ea3bc930432750108
+ uses: ruby/setup-ruby@v1
  with:
  ruby-version: ${{ matrix.ruby-version }}
  - name: Install dependencies

.tool-versions

@@ -1 +1 @@
-ruby 3.1.0
+ruby 3.3.4

Gemfile

@@ -23,5 +23,5 @@ if rails_version.start_with? "6"
 end
 gem "rails", rails_constraint
 gem "sprockets-rails"
-gem "sqlite3"
+gem "sqlite3", "~> 1.4"
 gem "standardrb"