[match] fix nuke exception when nuking with the empty files storage

[crazymanish]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

• Closes: undefined method `count' for nil:NilClass in nuke  #18863
• Nuke is failing with exception when nuking with the empty files storage
• In this line#256 because files_to_delete was nil in this line#251

Description

• Now, initializing files_to_delete with [] if needed.
  Please note: I notice there is no spec file for this nuke.rb 🤯 I will be adding all the unit-tests for all the FastlaneTools once I will finish Fastlane actions' is_string deprecation goal!

Testing Steps

• I don't know exactly... 🤷‍♂️
• maybe create a new certificate manually? and don't store that in git-repo and run nuke 😜🤨

[joshdholtz]

This looks great to me! Thank you for fixing 😊

[fastlane-bot]

Congratulations! 🎉 This was released as part of fastlane 2.186.0 🚀