Support netstandard2.1 (#5)

* add IsExternalInit to support older target frameworks

* add net5.0 and netstandard2.1 framework targets

* remove explicit net5.0 target

* remove explicit net6.0 target

src/Ephemerally.Azure.Cosmos/Ephemerally.Azure.Cosmos.csproj

@@ -1,27 +1,31 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>netstandard2.1</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>disable</Nullable>
-    <LangVersion>latest</LangVersion>
+    <LangVersion>11</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Azure.Cosmos" Version="3.26.0" />
-    <PackageReference Include="minver" Version="4.3.0">
-      <PrivateAssets>all</PrivateAssets>
-      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-    </PackageReference>
-    <PackageReference Include="System.Linq.Async" Version="6.0.1" />
+    <InternalsVisibleTo Include="$(AssemblyName).Tests" />
   </ItemGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\Ephemerally.Azure\Ephemerally.Azure.csproj" />
   </ItemGroup>
-
+  
   <ItemGroup>
-    <InternalsVisibleTo Include="$(AssemblyName).Tests" />
+    <PackageReference Include="IsExternalInit" Version="1.0.3">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.Azure.Cosmos" Version="3.34.0" />
+    <PackageReference Include="minver" Version="4.3.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="System.Linq.Async" Version="6.0.1" />
   </ItemGroup>
 
 </Project>

src/Ephemerally.Azure/Ephemerally.Azure.csproj

@@ -1,20 +1,25 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>netstandard2.1</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
+    <Nullable>disable</Nullable>
+    <LangVersion>11</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\Ephemerally\Ephemerally.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="IsExternalInit" Version="1.0.3">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
     <PackageReference Include="minver" Version="4.3.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
   </ItemGroup>
 
-  <ItemGroup>
-    <ProjectReference Include="..\Ephemerally\Ephemerally.csproj" />
-  </ItemGroup>
-
 </Project>

src/Ephemerally/Ephemerally.csproj

@@ -1,18 +1,21 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>netstandard2.1</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>disable</Nullable>
-    <LangVersion>latest</LangVersion>
-    <EnablePreviewFeatures>true</EnablePreviewFeatures>
+    <LangVersion>11</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
     <InternalsVisibleTo Include="$(AssemblyName).Tests" />
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="IsExternalInit" Version="1.0.3">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
     <PackageReference Include="minver" Version="4.3.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>