Fix tests

Author: NicolasDorier

NBitcoin.Tests/PSBTTests.cs

@@ -621,8 +621,6 @@ public void CanHandleUnKnown()
 			data1.Combine(data2);
 			var expected = PSBT.Parse((string)testdata["psbtUnknown2"], Network.Main);
 			Assert.Equal(data1, expected, ComparerInstance);
-
-
 		}
 		[Fact]
 		[Trait("UnitTest", "UnitTest")]

NBitcoin/BIP174/PSBTInput.cs

@@ -602,9 +602,7 @@ internal virtual void FillMap(Map map)
 
 			// Write unknown things
 			foreach (var kv in unknown)
-			{
 				map.Add(kv.Key, kv.Value);
-			}
 		}
 
 		#endregion

NBitcoin/BIP174/PSBTOutput.cs

@@ -128,7 +128,7 @@ internal virtual void FillMap(Map map)
 				map.Add(key, b);
 			}
 			foreach (var kv in unknown)
-				unknown.Add(kv.Key, kv.Value);
+				map.Add(kv.Key, kv.Value);
 		}
 
 		#endregion

NBitcoin/BIP174/PartiallySignedTransaction.cs

@@ -855,18 +855,12 @@ internal virtual void FillMap(Map map)
 				map.Add(key, value);
 			}
 			foreach (var kv in Unknown)
-			{
 				map.Add(kv.Key, kv.Value);
-			}
 		}
 		internal void FillMaps(Maps maps)
 		{
 			var globalMap = maps.NewMap();
 			FillMap(globalMap);
-			foreach (var kv in Unknown)
-			{
-				globalMap.Add(kv.Key, kv.Value);
-			}
 			// Write inputs
 			foreach (var psbtin in Inputs)
 			{