Fix test to remove hardcoded Mac path

Remove hardcoded /Users/adz/Documents path from xlsx test that was
causing CI failures on Linux. The test now only verifies the output
exists without writing to a specific file path.

Fixes GitHub Actions test failures on all platforms.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: adz624

test/export_user_test.rb

@@ -45,7 +45,6 @@ def amount
 
   describe "#to_xlsx" do
     should "will not throw exception" do
-      File.open('/Users/adz/Documents/xxxx.xlsx', 'wb') {|f| f.write(@export.to_xlsx) }
       assert @export.to_xlsx.present?
     end
   end