feat: abra release now asks for a release note (!393)

This implements coop-cloud/organising#540 by checking if a`release/next` file exists and if so moves it to `release/<tag>`. When no release notes exists it prompts for them.

Reviewed-on: coop-cloud/abra#393
Reviewed-by: moritz <moritz.m@local-it.org>
Co-authored-by: p4u1 <p4u1_f4u1@riseup.net>
Co-committed-by: p4u1 <p4u1_f4u1@riseup.net>

pkg/git/add.go

@@ -0,0 +1,27 @@
+package git
+
+import (
+	"github.com/go-git/go-git/v5"
+	"github.com/sirupsen/logrus"
+)
+
+// Add adds a file to the git index.
+func Add(repoPath, path string, dryRun bool) error {
+	repo, err := git.PlainOpen(repoPath)
+	if err != nil {
+		return err
+	}
+
+	worktree, err := repo.Worktree()
+	if err != nil {
+		return err
+	}
+
+	if dryRun {
+		logrus.Debugf("dry run: adding %s", path)
+	} else {
+		worktree.Add(path)
+	}
+
+	return nil
+}