Build(deps-dev): Bump rexml from 3.2.6 to 3.2.8 (#61)

Author: dependabot[bot]

Gemfile.lock

@@ -24,7 +24,8 @@ GEM
     racc (1.7.3)
     rainbow (3.1.1)
     regexp_parser (2.9.0)
-    rexml (3.2.6)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rspec (3.13.0)
       rspec-core (~> 3.13.0)
       rspec-expectations (~> 3.13.0)
@@ -74,6 +75,7 @@ GEM
       unicode-display_width (>= 1.5, < 3.0)
       unicode_utils (~> 1.4)
     strings-ansi (0.2.0)
+    strscan (3.1.0)
     tty-box (0.7.0)
       pastel (~> 0.8)
       strings (~> 0.2.0)