feat: Automatically assign Pull Requests to GitHub Milestones

When building a Pull Request in CI, automatically assign the Pull Request being built to a GitHub milestone for the current version.

The name of the Milestone is determined from the version being built using the format 'v<MAJOR>.<MINOR>'.

Pull-Request: #26

src/SharedBuild/TaskNames.cs

@@ -16,5 +16,6 @@ public static class TaskNames
         public const string ValidateCodeFormatting = "ValidateCodeFormatting";
         public const string Validate = "Validate";
         public const string Generate = "Generate";
+        public const string SetGitHubMilestone = "SetGitHubMilestone";
     }
 }

src/SharedBuild/Tasks/CITask.cs

@@ -12,6 +12,7 @@ namespace Grynwald.SharedBuild.Tasks
     [IsDependentOn(typeof(PackTask))]
     [IsDependentOn(typeof(GenerateChangeLogTask))]
     [IsDependentOn(typeof(PushTask))]
+    [IsDependentOn(typeof(SetGitHubMilestoneTask))]
     [IsDependentOn(typeof(CreateGitHubReleaseTask))]
     public class CITask : FrostingTask
     { }

src/SharedBuild/Tasks/SetGitHubMilestoneTask.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Threading.Tasks;
+using Cake.Core.Diagnostics;
+using Cake.Frosting;
+using Cake.GitHub;
+using Cake.GitVersioning;
+
+namespace Grynwald.SharedBuild.Tasks
+{
+    [TaskName(TaskNames.SetGitHubMilestone)]
+    public class SetGitHubMilestoneTask : AsyncFrostingTask<IBuildContext>
+    {
+        public override bool ShouldRun(IBuildContext context)
+        {
+            return context.IsRunningInCI && context.GitHub.PullRequest.IsPullRequest;
+        }
+
+
+        public override async Task RunAsync(IBuildContext context)
+        {
+            var versionInfo = context.GitVersioningGetVersion(context.RootDirectory.FullPath);
+            var milestoneTitle = $"v{versionInfo.Version.Major}.{versionInfo.Version.Minor}";
+
+            context.Log.Information($"Assinging Pull Request {context.GitHub.PullRequest.Number} to milestone {milestoneTitle}");
+
+            if (context.GitHub.TryGetAccessToken() is not string accessToken)
+            {
+                throw new Exception("No GitHub access token specified. Cannot set Milestone for Pull Request");
+            }
+
+            await context.GitHubSetMilestoneAsync(
+                userName: null,
+                accessToken,
+                context.GitHub.RepositoryOwner,
+                context.GitHub.RepositoryName,
+                context.GitHub.PullRequest.Number,
+                milestoneTitle,
+                new GitHubSetMilestoneSettings()
+                {
+                    Overwrite = true,
+                    CreateMilestone = true
+                });
+        }
+
+    }
+}