MorestachioFormatterService is not thread safe

[WizX20]

Describe the bug
The MorestachioFormatterService is not thread safe.

To Reproduce

XXX threw exception: 
System.TypeInitializationException: The type initializer for 'Morestachio.Formatter.Framework.MorestachioFormatterService' threw an exception. ---> System.TypeInitializationException: The type initializer for 'Morestachio.Formatter.Predefined.Accounting.CurrencyHandler' threw an exception. ---> System.ArgumentException: An item with the same key has already been added. Key: PYG
  Stack Trace:
      at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
   at Morestachio.Formatter.Predefined.Accounting.CurrencyHandler..cctor()
--- End of inner exception stack trace ---
    at Morestachio.Formatter.Predefined.Accounting.CurrencyHandler.get_DefaultHandler()
   at Morestachio.Formatter.Framework.MorestachioFormatterService..cctor()
--- End of inner exception stack trace ---
    at Morestachio.Formatter.Framework.MorestachioFormatterService..ctor(Boolean useCache)
   at Morestachio.ParserOptions..ctor(ITemplateContainer template, Func`2 sourceStream, Encoding encoding)
   at Morestachio.ParserOptions..ctor(ITemplateContainer template, Func`1 sourceStream, Encoding encoding)
   at Morestachio.ParserOptions..ctor(String template, Func`1 sourceStream, Encoding encoding)
   at Morestachio.ParserOptions..ctor(String template, Func`1 sourceStream)
   at Morestachio.ParserOptions..ctor(String template)

Expected behavior
Should use thread safe collections internally: https://docs.microsoft.com/en-us/dotnet/standard/collections/thread-safe/

[JPVenson]

That does not look like a thread problem to me, more like a duplicate in the currency map.

[JPVenson]

Hotfix is released by version 5.0.1.577. Could you please verify?

[WizX20]

Tested and deemed working! 🎉