Update Ruby version and fix test mock references

Author: JDrizzy

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.6, 2.7]
+        ruby: [3.3, 3.4, 4.0]
 
     steps:
       - uses: actions/checkout@v2

.ruby-version

@@ -1 +1 @@
-ruby-2.7.4
+3.4.5

lib/business_central.rb

@@ -19,3 +19,4 @@
 require 'business_central/exceptions'
 require 'business_central/client'
 require 'business_central/web_service'
+require 'business_central/version'

test/business_central/client_test.rb

@@ -84,7 +84,7 @@ def test_authorize_throws_exception
         body: { error: 'unknown error' }.to_json
       )
 
-    mock = MiniTest::Mock.new
+    mock = Minitest::Mock.new
     def mock.authorize_url(_arguments)
       response = Faraday.get(BusinessCentral::Client::DEFAULT_LOGIN_URL)
       response = OAuth2::Response.new(response)
@@ -106,7 +106,7 @@ def test_request_token_throws_exception
         body: { error: 'token error' }.to_json
       )
 
-    mock = MiniTest::Mock.new
+    mock = Minitest::Mock.new
     def mock.get_token(*_params)
       response = Faraday.get(BusinessCentral::Client::DEFAULT_URL)
       response = OAuth2::Response.new(response)