update target versions (#178)

Author: maximn

GoogleMapsApi.Test/GoogleMapsApi.Test.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-	<TargetFrameworks>net8.0;net6.0;net4.8</TargetFrameworks>
+	<TargetFrameworks>net8.0;net6.0;net481</TargetFrameworks>
     <LangVersion>latest</LangVersion>
     <OutputType>Library</OutputType>
     <IsPackable>false</IsPackable>

GoogleMapsApi/GoogleMapsApi.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-	<TargetFrameworks>net8.0;net7.0;net6.0;netstandard2.0</TargetFrameworks>
+	<TargetFrameworks>netstandard2.0;net6.0;net8.0;net481;net462</TargetFrameworks>
 	<LangVersion>latest</LangVersion>
 	<Version>0.0.0</Version>
 	<AppxAutoIncrementPackageRevision>True</AppxAutoIncrementPackageRevision>
@@ -35,4 +35,8 @@
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All"/>
   </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'net481' OR '$(TargetFramework)' == 'net462'">
+    <PackageReference Include="System.Net.Http" Version="4.3.4" />
+  </ItemGroup>
 </Project>