Upgrade project to .NET 7

Author: tomc128

BooleanExpressionParser/.vscode/launch.json

@@ -6,7 +6,7 @@
             "type": "coreclr",
             "request": "launch",
             "preLaunchTask": "build",
-            "program": "${workspaceFolder}/bin/Debug/net6.0/BooleanExpressionParser.dll",
+            "program": "${workspaceFolder}/bin/Debug/net7.0/BooleanExpressionParser.dll",
             "args": [
                 // "A.B",
                 // "A+B",

BooleanExpressionParser/BooleanExpressionParser.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>