Update target frameworks and project version to 9.0.0

- Removed net7.0 and added net9.0 as target frameworks.
- Updated project version from 8.2.1 to 9.0.0.
- Added conditional package reference for Microsoft.Extensions.Primitives 9.0.0 for net9.0.
- Modified existing package reference for Microsoft.Extensions.Primitives 7.0.0 to exclude net9.0.

Author: electricessence

Source/Open.Text.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
-		<TargetFrameworks>netstandard2.0;netstandard2.1;net6.0;net7.0;net8.0</TargetFrameworks>
+		<TargetFrameworks>netstandard2.0;netstandard2.1;net6.0;net8.0;net9.0</TargetFrameworks>
 		<LangVersion>latest</LangVersion>
 		<Nullable>enable</Nullable>
 		<ImplicitUsings>enable</ImplicitUsings>
@@ -20,7 +20,7 @@
 		<RepositoryUrl>https://github.com/Open-NET-Libraries/Open.Text</RepositoryUrl>
 		<RepositoryType>git</RepositoryType>
 		<PackageTags>string, span, enum, readonlyspan, text, format, split, trim, equals, trimmed equals, first, last, preceding, following, stringbuilder, extensions, stringcomparable, spancomparable, stringsegment, splitassegment</PackageTags>
-		<Version>8.2.1</Version>
+		<Version>9.0.0</Version>
 		<PackageReleaseNotes></PackageReleaseNotes>
 		<PackageLicenseExpression>MIT</PackageLicenseExpression>
 		<PublishRepositoryUrl>true</PublishRepositoryUrl>
@@ -31,14 +31,11 @@
 		<PackageReadmeFile>README.md</PackageReadmeFile>
 		<NoWarn>IDE0301;IDE0079;IDE0200;</NoWarn>
 	</PropertyGroup>
-
-	<PropertyGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
-		<NoWarn>$(NoWarn);nullable</NoWarn>
-	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="Microsoft.Extensions.Primitives" Version="7.0.0" />
 		<PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All" />
+		<PackageReference Include="Microsoft.Extensions.Primitives" Version="9.0.0" Condition="'$(TargetFramework)' == 'net9.0'" />
+		<PackageReference Include="Microsoft.Extensions.Primitives" Version="7.0.0" Condition="'$(TargetFramework)' != 'net9.0'" />
 	</ItemGroup>
 
 	<ItemGroup>