Allow emojis and accented characters in names and locations.

[ra314]

Updated the regex in Event to use Unicode properties (\p{L}, \p{N}, \p{S}). This allows names and locations to start with emojis or accented letters. Added unit tests for emoji and accented name validation.

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Hi there! Thanks so much for submitting a pull request!

Let's just make sure together that all of these boxes are checked before we
merge this change:

• [✓] The code in these changes works correctly.
• [✓] Code has tests as appropriate.
• [ x] Code has been reviewed by @JacobEvelyn.
• [ x] All tests pass on GitHub.
• [✓] Code coverage remains high.
• [✓] RuboCop reports no issues on GitHub.
• [ x] The README.md file is updated as appropriate.

Don't worry—this list will get checked off in no time!

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I ran the following and there were no issues.

bundle exec rubocop lib/friends/event.rb
bundle exec rake test

I also added unit tests to cover names that start with emoji.