Update rubocop requirement from ~> 1.28.2 to ~> 1.33.0

Updates the requirements on [rubocop](https://github.com/rubocop/rubocop) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop/rubocop/compare/v1.28.2...v1.33.0)

---
updated-dependencies:
- dependency-name: rubocop
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -43,6 +43,8 @@ GEM
     ffi (1.15.5-java)
     google-cloud-env (1.6.0)
       faraday (>= 0.17.3, < 3.0)
+    json (2.6.2)
+    json (2.6.2-java)
     method_source (1.0.0)
     mock_redis (0.32.0)
       ruby2_keywords
@@ -127,13 +129,14 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
-    rubocop (1.28.2)
+    rubocop (1.33.0)
+      json (~> 2.3)
       parallel (~> 1.10)
       parser (>= 3.1.0.0)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.8, < 3.0)
-      rexml
-      rubocop-ast (>= 1.17.0, < 2.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.19.1, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
     rubocop-ast (1.19.1)
@@ -175,7 +178,7 @@ DEPENDENCIES
   pry
   rack-test (>= 0.6)
   rspec (>= 3.2)
-  rubocop (~> 1.28.2)
+  rubocop (~> 1.33.0)
   simplecov (>= 0.11.2)
   thor (~> 1.0, >= 1.0.1)
   vmpooler!

vmpooler.gemspec

@@ -43,7 +43,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'pry'
   s.add_development_dependency 'rack-test', '>= 0.6'
   s.add_development_dependency 'rspec', '>= 3.2'
-  s.add_development_dependency 'rubocop', '~> 1.28.2'
+  s.add_development_dependency 'rubocop', '~> 1.33.0'
   s.add_development_dependency 'simplecov', '>= 0.11.2'
   s.add_development_dependency 'thor', '~> 1.0', '>= 1.0.1'
   s.add_development_dependency 'yarjuf', '>= 2.0'