Bump rexml from 3.3.7 to 3.3.9 in /Tests/InstallationTests/CocoapodsI…

…nstallation (#4418)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Tests/InstallationTests/CocoapodsInstallation/Gemfile.lock

@@ -244,7 +244,7 @@ GEM
       trailblazer-option (>= 0.1.1, < 0.2.0)
       uber (< 0.2.0)
     retriable (3.1.2)
-    rexml (3.3.7)
+    rexml (3.3.9)
     rouge (2.0.7)
     ruby-macho (2.5.1)
     ruby2_keywords (0.0.5)
@@ -272,10 +272,6 @@ GEM
       concurrent-ruby (~> 1.0)
     uber (0.1.0)
     unicode-display_width (2.6.0)
-    unf (0.1.4)
-      unf_ext
-    unf_ext (0.0.8)
-    webrick (1.8.2)
     word_wrap (1.0.0)
     xcodeproj (1.25.0)
       CFPropertyList (>= 2.3.3, < 4.0)