Update decimal status - yellow since there's the third-party mpy-decimal module

Standard-Library-Coverage.md

@@ -46,7 +46,7 @@
 | [dbm.dumb](https://docs.python.org/3/library/dbm.html#module-dbm.dumb) |  Portable implementation of the simple DBM interface. | ? | 
 | [dbm.gnu](https://docs.python.org/3/library/dbm.html#module-dbm.gnu) |  GNU's reinterpretation of dbm. | ? | 
 | [dbm.ndbm](https://docs.python.org/3/library/dbm.html#module-dbm.ndbm) |  The standard "database" interface, based on ndbm. | ? | 
-| [decimal](https://docs.python.org/3/library/decimal.html#module-decimal) |  Implementation of the General Decimal Arithmetic  Specification. | ? | 
+| [decimal](https://docs.python.org/3/library/decimal.html#module-decimal) |  Implementation of the General Decimal Arithmetic  Specification. | 🟡 | See third-part [mpy-decimal](https://github.com/mpy-dev/micropython-decimal-number).
 | [difflib](https://docs.python.org/3/library/difflib.html#module-difflib) |  Helpers for computing differences between objects. | ? | 
 | [dis](https://docs.python.org/3/library/dis.html#module-dis) |  Disassembler for Python bytecode. | ? | 
 | [distutils](https://docs.python.org/3/library/distutils.html#module-distutils) and submodules |  Support for building and installing Python modules into an existing Python installation. | ❌ |