Update Ruby language to v3.4.2 (#79)

Update README to point to Ruby version file to streamline future updates. 

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Tanner Doshier <git@doshitan.com>

Author: renovate[bot]

template/{{app_name}}/.rubocop.yml

@@ -4,4 +4,4 @@ inherit_gem:
   pundit: config/rubocop-rspec.yml
   rubocop-rails-omakase: rubocop.yml
 AllCops:
-  TargetRubyVersion: 3.3.7
+  TargetRubyVersion: 3.4.2

template/{{app_name}}/.ruby-version

@@ -1 +1 @@
-3.3.7
+3.4.2

template/{{app_name}}/Dockerfile.jinja

@@ -2,7 +2,7 @@
 
 # Make sure RUBY_VERSION matches the Ruby version in .ruby-version and Gemfile
 # renovate: datasource=docker depName=registry.docker.com/library/ruby
-ARG RUBY_VERSION=3.3.7
+ARG RUBY_VERSION=3.4.2
 
 
 ##########################################################################################

template/{{app_name}}/Gemfile

@@ -1,6 +1,6 @@
 source "https://rubygems.org"
 
-ruby "3.3.7"
+ruby "3.4.2"
 
 # Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
 gem "rails", "~> 7.1.3", ">= 7.1.3.2"

template/{{app_name}}/Gemfile.lock

@@ -495,7 +495,7 @@ DEPENDENCIES
   web-console
 
 RUBY VERSION
-   ruby 3.3.7p123
+   ruby 3.4.2p28
 
 BUNDLED WITH
    2.5.22

template/{{app_name}}/README.md.jinja

@@ -72,7 +72,7 @@ In either case, first generate a `.env` file:
 
 Prerequisites:
 
-- Ruby 3.3.7
+- Ruby version matching [`.ruby-version`](./.ruby-version)
 - [Node LTS](https://nodejs.org/en)
 - (Optional but recommended): [rbenv](https://github.com/rbenv/rbenv)