Update to 1.15.0 upstream release

Upstream tag: 1.15.0
Upstream commit: d507597e

Commit authored by Packit automation (https://packit.dev/)

plans/git_reference.py

@@ -0,0 +1,17 @@
+#!/usr/bin/python
+
+# Copyright Contributors to the Packit project.
+# SPDX-License-Identifier: MIT
+
+import subprocess
+from pathlib import Path
+
+import fmf
+
+tree_root = Path.cwd().absolute()
+node = fmf.Tree(tree_root).find("/plans")
+with node as data:
+    data["discover"]["url"] = "https://github.com/packit/packit.git"
+    data["discover"]["ref"] = (
+        subprocess.check_output(["git", "rev-parse", "HEAD"]).decode().strip()
+    )