Update git requirement from ~> 1.7 to >= 1.7, < 3.0

Updates the requirements on [git](https://github.com/ruby-git/ruby-git) to permit the latest version.
- [Release notes](https://github.com/ruby-git/ruby-git/releases)
- [Changelog](https://github.com/ruby-git/ruby-git/blob/master/CHANGELOG.md)
- [Commits](ruby-git/ruby-git@v1.7.0...v2.0.0)

---
updated-dependencies:
- dependency-name: git
  dependency-type: direct:production
...

Author: ekohl

lib/modulesync.rb

@@ -178,7 +178,7 @@ def self.update(cli_options)
     # managed_modules is either an array or a hash
     managed_modules.each do |puppet_module|
       manage_module(puppet_module, module_files, defaults)
-    rescue ModuleSync::Error, Git::GitExecuteError => e
+    rescue ModuleSync::Error, Git::Error => e
       message = e.message || 'Error during `update`'
       warn "#{puppet_module.given_name}: #{message}"
       exit 1 unless options[:skip_broken]

lib/modulesync/repository.rb

@@ -158,7 +158,7 @@ def submit_changes(files, options)
           repo.push('origin', branch, opts_push)
           puts "Changes have been pushed to: '#{branch}'"
         end
-      rescue Git::GitExecuteError => e
+      rescue Git::Error => e
         raise unless e.message.match?(/working (directory|tree) clean/)
 
         puts "There were no changes in '#{@directory}'. Not committing."

lib/monkey_patches.rb

@@ -2,9 +2,9 @@
 
 module Git
   module LibMonkeyPatch
-    # Monkey patch set_custom_git_env_variables due to our ::Git::GitExecuteError handling.
+    # Monkey patch set_custom_git_env_variables due to our ::Git::Error handling.
     #
-    # We rescue on the GitExecuteError and proceed differently based on the output of git.
+    # We rescue on the Git::Error and proceed differently based on the output of git.
     # This way makes code language-dependent, so here we ensure that Git gem throw git commands with the "C" language
     def set_custom_git_env_variables
       super

modulesync.gemspec

@@ -25,7 +25,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'simplecov', '~> 0.22.0'
   spec.add_development_dependency 'voxpupuli-rubocop', '~> 3.0.0'
 
-  spec.add_dependency 'git', '~>1.7'
+  spec.add_dependency 'git', '~> 1.7', '< 4'
   spec.add_dependency 'gitlab', '>=4', '<6'
   spec.add_dependency 'octokit', '>=4', '<10'
   spec.add_dependency 'puppet-blacksmith', '>= 3.0', '< 9'