Fix precondition header casing

Author: mikernet

Source/Singulink.Net.Http.Api.Client/ApiClientBase.cs

@@ -24,7 +24,7 @@ public abstract class ApiClientBase
     /// <see cref="SendAsync{TResponse}(HttpRequestMessage, object?, CancellationToken)"/> method before calling the base implementation. It matches the default
     /// key expected by <c>CookieSessionHandler</c>.
     /// </remarks>
-    protected const string DefaultUserIdPreconditionHeaderName = "If-User-ID";
+    protected const string DefaultUserIdPreconditionHeaderName = "If-User-Id";
 
     /// <summary>
     /// The default name of the cookie that holds the encrypted session token. Value is <c>"session-token"</c>.

Source/Singulink.Net.Http.Api.Client/Singulink.Net.Http.Api.Client.csproj

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <TargetFramework>net8.0</TargetFramework>
 
-    <Version>1.8</Version>
+    <Version>1.8.1</Version>
     <Description>API client library for the Singulink HTTP API Tookit.</Description>
     <PackageTags>HTTP; API; Client;</PackageTags>
   </PropertyGroup>