fix: test/Gemfile & test/Gemfile.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-REXML-7577227
- https://snyk.io/vuln/SNYK-RUBY-REXML-7577228

test/Gemfile

@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 group :lint do
-  gem 'mdl', '>= 0.7.0'
+  gem 'mdl', '>= 0.10.0'
 end
 
 group :integration do

test/Gemfile.lock

@@ -83,7 +83,7 @@ GEM
       test-kitchen (>= 1.0.0)
     kitchen-vagrant (1.3.2)
       test-kitchen (~> 1.4)
-    kramdown (2.3.0)
+    kramdown (2.4.0)
       rexml
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
@@ -92,17 +92,18 @@ GEM
     logging (2.2.2)
       little-plugger (~> 1.1)
       multi_json (~> 1.10)
-    mdl (0.9.0)
-      kramdown (~> 2.0)
-      kramdown-parser-gfm (~> 1.0)
+    mdl (0.13.0)
+      kramdown (~> 2.3)
+      kramdown-parser-gfm (~> 1.1)
       mixlib-cli (~> 2.1, >= 2.1.1)
       mixlib-config (>= 2.2.1, < 4)
+      mixlib-shellout
     minitar (0.9)
     mixlib-archive (1.0.5)
       mixlib-log
     mixlib-authentication (2.1.1)
-    mixlib-cli (2.1.6)
-    mixlib-config (3.0.6)
+    mixlib-cli (2.1.8)
+    mixlib-config (3.0.27)
       tomlrb
     mixlib-install (3.10.0)
       mixlib-shellout
@@ -147,7 +148,8 @@ GEM
     rack (2.2.3)
     rake (13.0.1)
     retryable (3.0.5)
-    rexml (3.2.5)
+    rexml (3.3.4)
+      strscan
     rspec (3.9.0)
       rspec-core (~> 3.9.0)
       rspec-expectations (~> 3.9.0)
@@ -187,6 +189,7 @@ GEM
       net-ssh (>= 2.7)
       net-telnet (= 0.1.1)
       sfl
+    strscan (3.1.0)
     syslog-logger (1.6.8)
     systemu (2.6.5)
     test-kitchen (1.22.0)
@@ -228,7 +231,7 @@ DEPENDENCIES
   berkshelf (>= 7.0.10)
   kitchen-docker
   kitchen-vagrant
-  mdl (>= 0.7.0)
+  mdl (>= 0.10.0)
   rake (>= 12.3.3)
   test-kitchen