Pin dotenv

pkgr.gemspec

@@ -27,6 +27,11 @@ Gem::Specification.new do |s|
   s.add_dependency('mixlib-shellout', '~> 1.4')
   # 5+ requires ruby 2.6+
   s.add_dependency('public_suffix', '~> 4')
+  # Fer el/8, old Ubuntus, SLES, etc.
+  # The last version of dotenv (>= 0) to support your Ruby & RubyGems was 2.8.1. Try installing it with `gem install dotenv -v 2.8.1` and then running the current command again
+  # dotenv requires Ruby version >= 3.0. The current ruby version is 2.7.7.221.
+  s.add_dependency('dotenv', '~> 2.8')
+
   s.add_development_dependency('rspec', '~> 3')
 
   s.files = Dir.glob("{lib,data}/**/*") + %w(LICENSE README.md)