Add pg per code review

Gemfile

@@ -24,15 +24,15 @@ gem 'jbuilder'
 # Use the Puma web server [https://github.com/puma/puma]
 gem 'puma', '>= 5.0'
 
+# Use postgres as the database for Active Record
+gem 'pg'
+
 # Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
 gem 'rails', '~> 7.1.2'
 
 # The original asset pipeline for Rails [https://github.com/rails/sprockets-rails]
 gem 'sprockets-rails'
 
-# Use sqlite3 as the database for Active Record
-gem 'sqlite3', '~> 1.4'
-
 # Hotwire's SPA-like page accelerator [https://turbo.hotwired.dev]
 gem 'turbo-rails'
 
@@ -81,6 +81,10 @@ group :development do
   # gem "rack-mini-profiler"
 end
 
+group :development, :test do
+  gem 'sqlite3'
+end
+
 group :test do
   # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
   gem 'capybara'

Gemfile.lock

@@ -187,6 +187,7 @@ GEM
     parser (3.2.2.4)
       ast (~> 2.4.1)
       racc
+    pg (1.5.4)
     psych (5.1.1.1)
       stringio
     public_suffix (5.0.3)
@@ -331,6 +332,7 @@ DEPENDENCIES
   http
   importmap-rails
   jbuilder
+  pg
   puma (>= 5.0)
   rails (~> 7.1.2)
   rubocop
@@ -340,7 +342,7 @@ DEPENDENCIES
   simplecov
   simplecov-lcov
   sprockets-rails
-  sqlite3 (~> 1.4)
+  sqlite3
   stimulus-rails
   turbo-rails
   tzinfo-data