Fix SPF Qualifier Neutral

Author: tinohager

src/Nager.EmailAuthentication/Models/Spf/Mechanisms/MechanismBase.cs

@@ -49,7 +49,7 @@ public void SetQualifier(char qualifier)
                     this.Qualifier = SpfQualifier.Fail;
                     return;
                 case '?':
-                    this.Qualifier = SpfQualifier.SoftFail;
+                    this.Qualifier = SpfQualifier.Neutral;
                     return;
                 default:
                     this.Qualifier = SpfQualifier.Unknown;

src/Nager.EmailAuthentication/Nager.EmailAuthentication.csproj

@@ -20,7 +20,7 @@
 
     <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
 
-    <Version>4.0.4</Version>
+    <Version>4.0.5</Version>
   </PropertyGroup>
 
   <ItemGroup>