refactor: remove SVN support

No Ruby projects have used SVN since ~2015. Removes 25 lines of
dead code including svn info parsing and pristine file lookup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pftg

lib/capybara/screenshot/diff/vcs.rb

@@ -7,15 +7,7 @@ module Screenshot
     module Diff
       module Vcs
         def self.checkout_vcs(root, screenshot_path, checkout_path)
-          if svn?(root)
-            restore_svn_revision(screenshot_path, checkout_path)
-          else
-            restore_git_revision(screenshot_path, checkout_path, root: root)
-          end
-        end
-
-        def self.svn?(root)
-          (root / ".svn").exist?
+          restore_git_revision(screenshot_path, checkout_path, root: root)
         end
 
         SILENCE_ERRORS = Os::ON_WINDOWS ? "2>nul" : "2>/dev/null"
@@ -45,27 +37,6 @@ def self.restore_git_revision(screenshot_path, checkout_path = screenshot_path,
           end
         end
 
-        def self.restore_svn_revision(screenshot_path, checkout_path)
-          committed_file_name = screenshot_path + "../.svn/text-base/" + "#{screenshot_path.basename}.svn-base"
-          if committed_file_name.exist?
-            FileUtils.cp(committed_file_name, checkout_path)
-            return true
-          end
-
-          svn_info = `svn info #{screenshot_path} #{SILENCE_ERRORS}`
-          unless svn_info.empty?
-            wc_root = svn_info.slice(/(?<=Working Copy Root Path: ).*$/)
-            checksum = svn_info.slice(/(?<=Checksum: ).*$/)
-
-            if checksum
-              committed_file_name = "#{wc_root}/.svn/pristine/#{checksum[0..1]}/#{checksum}.svn-base"
-              FileUtils.cp(committed_file_name, checkout_path)
-              return true
-            end
-          end
-
-          false
-        end
       end
     end
   end