chore(ruby): upgrade to ruby 3.3

- fix error due to tar files being frozen strings

.circleci/config.yml

@@ -18,7 +18,7 @@ executors:
         default: false
 
     docker:
-      - image: cimg/ruby:3.1.4-browsers
+      - image: cimg/ruby:3.3.5-browsers
         environment:
           PG_HOST: localhost
           PG_USER: ubuntu

Gemfile

@@ -1,7 +1,12 @@
 # frozen_string_literal: true
 source 'https://rubygems.org'
 
-ruby '3.1.4'
+ruby '3.3.5'
+
+# These gems are included in Ruby defaults for now,
+# but they will have to be included separately in future versions.
+gem 'ostruct'
+gem 'csv'
 
 # For Windows devs
 gem 'tzinfo-data', platforms: [:mswin, :mswin64]

Gemfile.lock

@@ -189,6 +189,7 @@ GEM
     coursemology-polyglot (0.3.8)
       activesupport (>= 4.2)
     crass (1.0.6)
+    csv (3.2.8)
     date (3.3.4)
     devise (4.9.4)
       bcrypt (~> 3.0)
@@ -372,6 +373,7 @@ GEM
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     orm_adapter (0.5.0)
+    ostruct (0.6.0)
     parallel (1.26.3)
     parallel_tests (4.7.1)
       parallel
@@ -630,6 +632,7 @@ DEPENDENCIES
   codecov
   consistency_fail
   coursemology-polyglot
+  csv
   devise (= 4.9.4)
   devise-multi_email
   docker-api
@@ -660,6 +663,7 @@ DEPENDENCIES
   mimemagic (= 0.4.3)
   mini_magick
   nokogiri (>= 1.8.1)
+  ostruct
   parallel_tests
   pg
   puma
@@ -703,7 +707,7 @@ DEPENDENCIES
   yard
 
 RUBY VERSION
-   ruby 3.1.4p223
+   ruby 3.3.5p100
 
 BUNDLED WITH
    2.5.9

lib/autoload/coursemology_docker_container.rb

@@ -202,7 +202,8 @@ def extract_test_report(report_path)
     tar_file = Gem::Package::TarReader.new(stream)
     tar_file.each do |file|
       test_report = file.read
-      return test_report.force_encoding(Encoding::UTF_8) if test_report
+      # this string must be mutable for force_encoding to work
+      return (+test_report).force_encoding(Encoding::UTF_8) if test_report
     end
   rescue Docker::Error::NotFoundError
     nil