update .NET Framework version to 4.6.2

* 4.0 and 4.5 are out of support by now,
  4.6.2 is the oldest version that is stil supported
* see https://learn.microsoft.com/en-us/lifecycle/products/microsoft-net-framework
* also 4.6.2 is required to update the dependecies to the latest versions

Author: janusw

src/GeoJSON.Net.Tests/GeoJSON.Net.Tests.csproj

@@ -1,10 +1,10 @@
 <Project Sdk="Microsoft.NET.Sdk" ToolsVersion="15.0">
   <PropertyGroup>
-    
+
     <ProjectGuid>{6C93B314-9208-4684-B873-172F7EC81689}</ProjectGuid>
     <RootNamespace>GeoJSON.Net.Tests</RootNamespace>
     <AssemblyName>GeoJSON.Net.Tests</AssemblyName>
-    <TargetFrameworks>net45;netcoreapp3.1</TargetFrameworks>
+    <TargetFrameworks>net462;netcoreapp3.1</TargetFrameworks>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
   </PropertyGroup>
   <ItemGroup>
@@ -27,4 +27,4 @@
   <ItemGroup>
     <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
 </ItemGroup>
-</Project>
+</Project>

src/GeoJSON.Net/GeoJSON.Net.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard1.0;netstandard1.1;netstandard2.0;netstandard2.1;net40;net45;net5.0</TargetFrameworks>
+    <TargetFrameworks>netstandard1.0;netstandard1.1;netstandard2.0;netstandard2.1;net462;net5.0</TargetFrameworks>
     <Description>.Net types for the GeoJSON RFC to be used with Json.Net</Description>
     <Authors>Matt Hunt;Joerg Battermann;Xavier Fischer</Authors>
     <Company>GeoJSON.Net</Company>
@@ -23,4 +23,4 @@
   <PropertyGroup>
     <FrameworkPathOverride Condition="'$(TargetFramework)' == 'net35'">$(MSBuildProgramFiles32)\Reference Assemblies\Microsoft\Framework\.NETFramework\v3.5\Profile\Client</FrameworkPathOverride>
   </PropertyGroup>
-</Project>
+</Project>