Read .ruby-version file in Gemfile

[dcangulo]

Summary

When updating the Ruby version, 2 files are always needed to be updated (.ruby-version and Gemfile). When not in sync it can lead to an error like Your Ruby version is 2.7.6, but your Gemfile specified 2.7.5.

This lessens the files that need to be updated when upgrading the Ruby version and makes it in sync always. It makes the .ruby-version the source of truth.

Example 1:

When upgrading from 0.70.0 to 0.71.0-rc.0. 2 files needs to be updated when it could have been just 1.

Source: https://react-native-community.github.io/upgrade-helper/?from=0.70.0&to=0.71.0-rc.0

Example 2:

21c8837 updates 4 files (.ruby-version, Gemfile, template/Gemfile, template/_ruby-version) when it could have been just 2.

Other Sources:

• https://andycroll.com/ruby/read-ruby-version-in-your-gemfile/
• https://render.com/docs/ruby-version (Heroku alternative)
• https://stackoverflow.com/a/35823132/9375533

Changelog

[General] [Changed] - Read .ruby-version file in Gemfile

Test Plan

Only .ruby-version and template/_ruby-version needs to be updated when upgrading Ruby version.

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
ios	-	universal	n/a	--

Base commit: 81e441a
Branch: main

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	7,102,440	+0
android	hermes	armeabi-v7a	6,470,493	+0
android	hermes	x86	7,519,895	+0
android	hermes	x86_64	7,378,573	+0
android	jsc	arm64-v8a	8,967,309	+0
android	jsc	armeabi-v7a	7,698,152	+0
android	jsc	x86	9,029,418	+0
android	jsc	x86_64	9,507,263	+0

Base commit: 81e441a
Branch: main

[pull-bot]

PR build artifact for 3875a23 is ready.
To use, download tarball from "Artifacts" tab in this CircleCI job then run yarn add <path to tarball> in your React Native project.

[pull-bot]

PR build artifact for 3875a23 is ready.
To use, download tarball from "Artifacts" tab in this CircleCI job then run yarn add <path to tarball> in your React Native project.

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