Fix Sequence->snap()->toSet() being lazy

[Baptouuuu]

Problem

In #54 the Sequence->snap()->toSet() was thought to be safe of using a lazy Set as the underlying value was correctly memoized.

The problem is that any transformation applied on it is now lazy. Meaning that if a transformation implies creating an object then these objects are re-created each time.

This is problematic for formal/orm as it relies on object identity to know what to persist.

Solution

->snap() is applied on the lazy Set to make sure everything is kept in memory.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.15%. Comparing base (fe00ac8) to head (150b761).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop      #55      +/-   ##
=============================================
- Coverage      97.23%   97.15%   -0.09%     
  Complexity      1062     1062              
=============================================
  Files             75       75              
  Lines           5252     5268      +16     
=============================================
+ Hits            5107     5118      +11     
- Misses           145      150       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.