Update rubocop requirement from ~> 0.92.0 to ~> 1.0.0 (#34)

Updates the requirements on [rubocop](https://github.com/rubocop-hq/rubocop) to permit the latest version.
- [Release notes](https://github.com/rubocop-hq/rubocop/releases)
- [Changelog](https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v0.92.0...v1.0.0)

* Require ruby 2.6+

Signed-off-by: Marc Qualie <marc@marcqualie.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Marc Qualie <marc@marcqualie.com>

Author: dependabot[bot]

.rubocop.yml

@@ -1,5 +1,6 @@
 AllCops:
   NewCops: enable
+  TargetRubyVersion: 2.6
 
 Style/ClassAndModuleChildren:
   Exclude:

Gemfile

@@ -7,6 +7,6 @@ gemspec
 
 gem 'minitest', '~> 5.0'
 gem 'rake', '~> 13.0'
-gem 'rubocop', '~> 0.92.0'
+gem 'rubocop', '~> 1.0.0'
 gem 'simplecov', '~> 0.19.0', require: false # CodeClimate not compatible with 0.18+ yet - https://github.com/codeclimate/test-reporter/issues/413
 gem 'simplecov-lcov', '< 0.8'

diffcrypt.gemspec

@@ -12,7 +12,7 @@ Gem::Specification.new do |spec|
   spec.description   = 'Diffable encrypted configuration files that can be safely committed into a git repository'
   spec.homepage      = 'https://github.com/marcqualie/diffcrypt'
   spec.license       = 'MIT'
-  spec.required_ruby_version = Gem::Requirement.new('>= 2.5.0')
+  spec.required_ruby_version = Gem::Requirement.new('>= 2.6.0')
 
   # spec.metadata["allowed_push_host"] = "TODO: Set to 'http://mygemserver.com'"