update ruby version in gemfile and docs

[stefandecimelli]

Description

Updates the ruby version for the doc server in order to fix dependency issue

Addressed Issue

fixes: https://github.com/DependencyTrack/dependency-track/issues/4247

• [x] I have read and understand the contributing guidelines
• [x] This PR fixes a defect, and I have provided tests to verify that the fix is effective
• [ ] This PR implements an enhancement, and I have provided tests to verify that it works as intended
• [ ] This PR introduces changes to the database model, and I have added corresponding update logic
• [x] This PR introduces new or alters existing behavior, and I have updated the documentation accordingly

[stefandecimelli]

Log for proof of working:

$ docker run --rm -it --name jekyll -p "127.0.0.1:4000:4000" -v "$(pwd)/docs:/srv/jekyll:Z" jekyll/jekyll:4.2.2 jekyll serve

Fetching gem metadata from https://rubygems.org/...........
Using bundler 2.3.25
Fetching public_suffix 6.0.1
Using colorator 1.1.0
Fetching concurrent-ruby 1.3.4
Installing public_suffix 6.0.1
Installing concurrent-ruby 1.3.4
Fetching csv 3.3.0
Using eventmachine 1.2.7
Using http_parser.rb 0.8.0
Fetching ffi 1.17.0 (x86_64-linux-musl)
Installing csv 3.3.0
Using forwardable-extended 2.6.0
Using rb-fsevent 0.11.2
Fetching rexml 3.3.8
Installing ffi 1.17.0 (x86_64-linux-musl)
Installing rexml 3.3.8
Fetching liquid 4.0.4
Using mercenary 0.3.6
Using rouge 3.30.0
Using safe_yaml 1.0.5
Fetching webrick 1.8.2
Installing webrick 1.8.2
Installing liquid 4.0.4
Fetching jekyll-mermaid 1.0.0
Fetching addressable 2.8.7
Installing jekyll-mermaid 1.0.0
Fetching i18n 1.14.6
Installing addressable 2.8.7
Using em-websocket 0.5.3
Using pathutil 0.16.2
Fetching rb-inotify 0.11.1
Installing rb-inotify 0.11.1
Installing i18n 1.14.6
Using kramdown 2.4.0
Using sass-listen 4.0.0
Fetching listen 3.9.0
Using kramdown-parser-gfm 1.1.0
Using sass 3.7.4
Using jekyll-sass-converter 1.5.2
Installing listen 3.9.0
Using jekyll-watch 2.2.1
Fetching jekyll 3.10.0
Installing jekyll 3.10.0
Using jekyll-feed 0.17.0
Using jekyll-redirect-from 0.16.0
Using jekyll-seo-tag 2.8.0
Using jekyll-sitemap 1.4.0
Bundle complete! 7 Gemfile dependencies, 34 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
ruby 3.1.1p18 (2022-02-18 revision 53f5fc4236) [x86_64-linux-musl]
Configuration file: /srv/jekyll/_config.yml
            Source: /srv/jekyll
       Destination: /srv/jekyll/_site
 Incremental build: disabled. Enable with --incremental
      Generating... 
       Jekyll Feed: Generating feed for posts
                    done in 2.143 seconds.
                    Auto-regeneration may not work on some Windows versions.
                    Please see: https://github.com/Microsoft/BashOnWindows/issues/216
                    If it does not work, please upgrade Bash on Windows or run Jekyll with --no-watch.
 Auto-regeneration: enabled for '/srv/jekyll'
    Server address: http://0.0.0.0:4000
  Server running... press ctrl-c to stop.