Restore suppor for Ruby 2.7

Signed-off-by: Amauri Bizerra <10775696+extern-c@users.noreply.github.com>

Author: extern-c

.github/workflows/ruby.yml

@@ -24,6 +24,7 @@ jobs:
           - '3.2.9'
           - '3.1.7'
           - '3.0.7'
+          - '2.7.8'
 
     steps:
     - uses: actions/checkout@v3

cyclonedx-ruby.gemspec

@@ -12,7 +12,7 @@ Gem::Specification.new do |spec|
   spec.description = 'CycloneDX is a lightweight software bill-of-material (SBOM) specification designed for use in application security contexts and supply chain component analysis. This Gem generates CycloneDX BOMs from Ruby projects.'
   spec.homepage    = 'https://github.com/CycloneDX/cyclonedx-ruby-gem'
   spec.license     = 'Apache-2.0'
-  spec.required_ruby_version = '>= 3.0'
+  spec.required_ruby_version = '>= 2.7.0'
 
   spec.metadata["homepage_uri"] = "https://github.com/CycloneDX/cyclonedx-ruby-gem?tab=readme-ov-file#readme"
   spec.metadata["source_code_uri"] = "https://github.com/CycloneDX/cyclonedx-ruby-gem/tree/v#{spec.version}"