[BUG] Gem depends on the lastest version of Ruby (3.3.1) which breaks the installation via brew

**Describe the bug** `doing` gem seems to be dependent on a non-specified version of `ruby` which makes it pull the latest one, and from what I understand Ruby > 3.1 doesn't have any longer the `exists?` method, which breaks the installation. **To Reproduce** Just run the installation as described in the Wiki: ``` ➤ brew gem install doing ==> Fetching dependencies for gem-doing: libyaml, ca-certificates, openssl@3 and ruby ==> Fetching libyaml ==> Downloading https://ghcr.io/v2/homebrew/core/libyaml/manifests/0.2.5 ######################################################################### 100.0% ==> Downloading https://ghcr.io/v2/homebrew/core/libyaml/blobs/sha256:98c0cf81bc ######################################################################### 100.0% ==> Fetching ca-certificates ==> Downloading https://ghcr.io/v2/homebrew/core/ca-certificates/manifests/2024- ######################################################################### 100.0% ==> Downloading https://ghcr.io/v2/homebrew/core/ca-certificates/blobs/sha256:ca ######################################################################### 100.0% ==> Fetching openssl@3 ==> Downloading https://ghcr.io/v2/homebrew/core/openssl/3/manifests/3.3.0-1 ######################################################################### 100.0% ==> Downloading https://ghcr.io/v2/homebrew/core/openssl/3/blobs/sha256:ec6f9daf ######################################################################### 100.0% ==> Fetching ruby ==> Downloading https://ghcr.io/v2/homebrew/core/ruby/manifests/3.3.1 ######################################################################### 100.0% ==> Downloading https://ghcr.io/v2/homebrew/core/ruby/blobs/sha256:737689c80a9c9 ######################################################################### 100.0% ==> Fetching gem-doing ==> Fetching doing from gem source Fetching doing-2.1.86.gem Downloaded doing-2.1.86 Warning: Cannot verify integrity of 'doing-2.1.86.gem'. No checksum was provided. For your reference, the checksum is: sha256 "0e4873e94625bdcdc438657a04c34f66757753bce0a49f19b7bb6a49282d88c0" ==> Installing dependencies for gem-doing: libyaml, ca-certificates, openssl@3 and ruby ==> Installing gem-doing dependency: libyaml ==> Downloading https://ghcr.io/v2/homebrew/core/libyaml/manifests/0.2.5 Already downloaded: /Users/<user>/Library/Caches/Homebrew/downloads/5f6b0af1730aa1bc02f8021c90ed7ffe988eeba95eec83e6c828f77332ba6406--libyaml-0.2.5.bottle_manifest.json ==> Pouring libyaml--0.2.5.arm64_sonoma.bottle.tar.gz 🍺 /opt/homebrew/Cellar/libyaml/0.2.5: 11 files, 354.9KB ==> Installing gem-doing dependency: ca-certificates ==> Downloading https://ghcr.io/v2/homebrew/core/ca-certificates/manifests/2024- Already downloaded: /Users/<user>/Library/Caches/Homebrew/downloads/c431e0186df2ccc2ea942b34a3c26c2cebebec8e07ad6abdae48447a52c5f506--ca-certificates-2024-03-11.bottle_manifest.json ==> Pouring ca-certificates--2024-03-11.all.bottle.tar.gz ==> Regenerating CA certificate bundle from keychain, this may take a while... 🍺 /opt/homebrew/Cellar/ca-certificates/2024-03-11: 4 files, 232.3KB ==> Installing gem-doing dependency: openssl@3 ==> Downloading https://ghcr.io/v2/homebrew/core/openssl/3/manifests/3.3.0-1 Already downloaded: /Users/<user>/Library/Caches/Homebrew/downloads/cd7e4cb72da375d51619d8c60fb91a70696e352edb515631b5751d05342e471d--openssl@3-3.3.0-1.bottle_manifest.json ==> Pouring openssl@3--3.3.0.arm64_sonoma.bottle.1.tar.gz 🍺 /opt/homebrew/Cellar/openssl@3/3.3.0: 6,977 files, 32.4MB ==> Installing gem-doing dependency: ruby ==> Downloading https://ghcr.io/v2/homebrew/core/ruby/manifests/3.3.1 Already downloaded: /Users/<user>/Library/Caches/Homebrew/downloads/844452a66e10bb7cb2dcc8942491cf29cf39ee3e4f47e379bd22f1ff461e30e4--ruby-3.3.1.bottle_manifest.json ==> Pouring ruby--3.3.1.arm64_sonoma.bottle.tar.gz 🍺 /opt/homebrew/Cellar/ruby/3.3.1: 19,716 files, 51.4MB ==> Installing gem-doing Error: An exception occurred within a child process: NoMethodError: undefined method `exists?' for class File ``` **Expected behavior** Gem `doing` should be installed without any errors **Desktop (please complete the following information):** - Platform: Mac - OS: Sonoma - Version 14.3 **Doing version** - Result of `doing -v` **Ruby version** - Result of `ruby -v` **Additional context** Add any other context about the problem here.