wip: try upgrading dependencies for ruby 3.4

with bundler 2.4.x for ruby 2.7

```
 /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/minitest-5.15.0/lib/minitest.rb:3:in 'Kernel#require': cannot load such file -- mutex_m (LoadError)
	from /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/minitest-5.15.0/lib/minitest.rb:3:in '<top (required)>'
	from /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/minitest-5.15.0/lib/minitest/autorun.rb:8:in 'Kernel#require'
	from /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/minitest-5.15.0/lib/minitest/autorun.rb:8:in '<top (required)>'
	from /home/runner/work/json_schemer/json_schemer/test/test_helper.rb:14:in 'Kernel#require'
	from /home/runner/work/json_schemer/json_schemer/test/test_helper.rb:14:in '<top (required)>'
	from /home/runner/work/json_schemer/json_schemer/test/configuration_test.rb:1:in 'Kernel#require'
	from /home/runner/work/json_schemer/json_schemer/test/configuration_test.rb:1:in '<top (required)>'
	from /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/rake-13.1.0/lib/rake/rake_test_loader.rb:21:in 'Kernel#require'
	from /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/rake-13.1.0/lib/rake/rake_test_loader.rb:21:in 'block in <main>'
	from /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/rake-13.1.0/lib/rake/rake_test_loader.rb:6:in 'Array#select'
	from /home/runner/work/json_schemer/json_schemer/vendor/bundle/ruby/3.4.0/gems/rake-13.1.0/lib/rake/rake_test_loader.rb:6:in '<main>'
```

Gemfile.lock

@@ -11,24 +11,24 @@ GEM
   remote: https://rubygems.org/
   specs:
     base64 (0.2.0)
-    bigdecimal (3.1.8)
-    bigdecimal (3.1.8-java)
-    concurrent-ruby (1.2.2)
-    csv (3.2.8)
-    docile (1.4.0)
+    bigdecimal (3.1.9)
+    bigdecimal (3.1.9-java)
+    concurrent-ruby (1.3.5)
+    csv (3.3.2)
+    docile (1.4.1)
     hana (1.3.7)
-    i18n (1.14.1)
+    i18n (1.14.6)
       concurrent-ruby (~> 1.0)
     i18n-debug (1.2.0)
       i18n (< 2)
-    minitest (5.15.0)
-    rake (13.1.0)
-    regexp_parser (2.9.2)
+    minitest (5.25.4)
+    rake (13.2.1)
+    regexp_parser (2.10.0)
     simplecov (0.22.0)
       docile (~> 1.1)
       simplecov-html (~> 0.11)
       simplecov_json_formatter (~> 0.1)
-    simplecov-html (0.12.3)
+    simplecov-html (0.13.1)
     simplecov_json_formatter (0.1.4)
     simpleidn (0.2.3)
 
@@ -38,7 +38,7 @@ PLATFORMS
 
 DEPENDENCIES
   base64
-  bundler (~> 2.0)
+  bundler (~> 2.4.0)
   csv
   i18n
   i18n-debug
@@ -48,4 +48,4 @@ DEPENDENCIES
   simplecov (~> 0.22)
 
 BUNDLED WITH
-   2.3.27
+   2.4.22

json_schemer.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |spec|
   spec.required_ruby_version = '>= 2.7'
 
   spec.add_development_dependency "base64"
-  spec.add_development_dependency "bundler", "~> 2.0"
+  spec.add_development_dependency "bundler", "~> 2.4.0"
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "minitest", "~> 5.0"
   spec.add_development_dependency "simplecov", "~> 0.22"