Add explicit dependency on rexml to fix erb_lint dependency chain

Gemfile.lock

@@ -1,7 +1,8 @@
 PATH
   remote: .
   specs:
-    rubocop-katalyst (2.0.5)
+    rubocop-katalyst (2.1.0)
+      rexml
       rubocop
       rubocop-capybara
       rubocop-factory_bot
@@ -47,6 +48,7 @@ GEM
     rainbow (3.1.1)
     rake (13.2.1)
     regexp_parser (2.9.2)
+    rexml (3.3.7)
     rspec (3.13.0)
       rspec-core (~> 3.13.0)
       rspec-expectations (~> 3.13.0)

rubocop-katalyst.gemspec

@@ -2,7 +2,7 @@
 
 Gem::Specification.new do |s|
   s.name    = "rubocop-katalyst"
-  s.version = "2.0.5"
+  s.version = "2.1.0"
   s.authors = ["Katalyst Interactive"]
   s.email   = ["[email protected]"]
 
@@ -30,4 +30,8 @@ Gem::Specification.new do |s|
   s.add_dependency "rubocop-rake"
   s.add_dependency "rubocop-rspec"
   s.add_dependency "rubocop-rspec_rails"
+
+  # Undeclared dependency of erb_lint, used to be required by rubocop
+  # This can be removed again once https://github.com/Shopify/erb_lint/issues/371 is resolved
+  s.add_dependency "rexml"
 end