reintroudce 2.5 and make rubocop happy

Author: fedetaglia

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: ['2.6', '2.7']
+        ruby: ['2.5', '2.6', '2.7']
     name: Test ruby v${{ matrix.ruby }} support
     steps:
     - uses: actions/checkout@v1

.rubocop.yml

@@ -1,5 +1,5 @@
 AllCops:
-  TargetRubyVersion: 2.6
+  TargetRubyVersion: 2.5
 
 Style/Documentation:
   Enabled: false

bmt.gemspec

@@ -14,7 +14,7 @@ Gem::Specification.new do |spec|
   spec.homepage      = 'https://github.com/bugcrowd/vrt-ruby'
   spec.license       = 'MIT'
   spec.require_paths = ['lib']
-  spec.required_ruby_version = '>= 2.6'
+  spec.required_ruby_version = '>= 2.5'
 
   spec.add_development_dependency 'bundler', '~> 2.1'
   spec.add_development_dependency 'pry', '~> 0.11'