Add release notes and increment minor

Author: glucaci

ReleaseNotes/3.4.0.md

@@ -0,0 +1,55 @@
+# Workflow Core 3.4.0
+
+## Execute Workflow Middleware
+
+These middleware get run after each workflow execution and can be used to perform additional actions or build metrics/statistics for all workflows in your app.
+
+The following example illustrates how you can use a execute workflow middleware to build [prometheus](https://prometheus.io/) metrics.
+
+Note that you use `WorkflowMiddlewarePhase.ExecuteWorkflow` to specify that it runs after each workflow execution.
+
+**Important:** You should call `next` as part of the workflow middleware to ensure that the next workflow in the chain runs.
+
+```cs
+public class MetricsMiddleware : IWorkflowMiddleware
+{
+    private readonly ConcurrentHashSet<string>() _suspendedWorkflows =
+        new ConcurrentHashSet<string>();
+
+    private readonly Counter _completed;
+    private readonly Counter _suspended;
+
+    public MetricsMiddleware()
+    {
+        _completed = Prometheus.Metrics.CreateCounter(
+            "workflow_completed", "Workflow completed");
+
+        _suspended = Prometheus.Metrics.CreateCounter(
+            "workflow_suspended", "Workflow suspended");
+    }
+
+    public WorkflowMiddlewarePhase Phase =>
+        WorkflowMiddlewarePhase.ExecuteWorkflow;
+
+    public Task HandleAsync(
+        WorkflowInstance workflow,
+        WorkflowDelegate next)
+    {
+        switch (workflow.Status)
+        {
+            case WorkflowStatus.Complete:
+                if (_suspendedWorkflows.TryRemove(workflow.Id))
+                {
+                    _suspended.Dec();
+                }
+                _completed.Inc();
+                break;
+            case WorkflowStatus.Suspended:
+                _suspended.Inc();
+                break;
+        }
+
+        return next();
+    }
+}
+```

src/WorkflowCore/WorkflowCore.csproj

@@ -15,12 +15,12 @@
     <GenerateAssemblyCompanyAttribute>false</GenerateAssemblyCompanyAttribute>
     <GenerateAssemblyProductAttribute>false</GenerateAssemblyProductAttribute>
     <Description>Workflow Core is a light weight workflow engine targeting .NET Standard.</Description>
-    <Version>3.3.6</Version>
-    <AssemblyVersion>3.3.6.0</AssemblyVersion>
-    <FileVersion>3.3.6.0</FileVersion>
+    <Version>3.4.0</Version>
+    <AssemblyVersion>3.4.0.0</AssemblyVersion>
+    <FileVersion>3.4.0.0</FileVersion>
     <PackageReleaseNotes></PackageReleaseNotes>
     <PackageIconUrl>https://github.com/danielgerlag/workflow-core/raw/master/src/logo.png</PackageIconUrl>
-    <PackageVersion>3.3.6</PackageVersion>
+    <PackageVersion>3.4.0</PackageVersion>
   </PropertyGroup>
 
   <ItemGroup>