Fix for using C# 8.0 projects (e.g. UWP projects stuck on .NET Core 3) - fixes #376

Author: zhuman

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.Execute.cs

@@ -978,7 +978,7 @@ private static FieldDeclarationSyntax CreateFieldDeclaration(string typeName, st
                 .AddVariables(
                     VariableDeclarator(Identifier(propertyName))
                     .WithInitializer(EqualsValueClause(
-                        ImplicitObjectCreationExpression()
+                        ObjectCreationExpression(IdentifierName(typeName))
                         .AddArgumentListArguments(Argument(
                             LiteralExpression(SyntaxKind.StringLiteralExpression, Literal(propertyName))))))))
                 .AddModifiers(