rexml gem is a bundled gem since Ruby 3.0.0. So we must add rexml to Gemfile

https://stackoverflow.com/questions/65479863/rails-6-1-ruby-3-0-0-tests-error-as-they-cannot-load-rexml

Author: emawby

DEVELOPING.md

@@ -14,7 +14,7 @@ The primary tests are located in `spec/osproject_spec.rb`, which contains the au
 Using RSpec, you can run test cases using `bin/rspec spec/osproject_spec.rb`. Note that the require paths are resolved according to the dir you're in when you're executing the code so running `bin/rspec spec/osproject_spec.rb` from inside the spec folder will not work.
 
 ## CLI
-CLI Behavior and business logic tests are located in `spec/oscli.rb`.
+CLI Behavior and business logic tests are located in `spec/osproject_spec.rb`.
 
 ## API
 API calls are not tested, as the API Client Library codebase handles this.

Gemfile

@@ -3,3 +3,4 @@ source 'https://rubygems.org'
 gem 'rspec'
 gem 'clamp'
 gem 'xcodeproj'
+gem 'rexml'

Gemfile.lock

@@ -8,6 +8,7 @@ GEM
     colored2 (3.1.2)
     diff-lcs (1.4.4)
     nanaimo (0.3.0)
+    rexml (3.2.4)
     rspec (3.10.0)
       rspec-core (~> 3.10.0)
       rspec-expectations (~> 3.10.0)
@@ -35,6 +36,7 @@ PLATFORMS
 
 DEPENDENCIES
   clamp
+  rexml
   rspec
   xcodeproj