Add blogpost for week 18 (#1135)

Author: majamassarini

weekly/2026/week-18.md

@@ -0,0 +1,13 @@
+---
+title: Week 18 in Packit
+date: 2026-05-05
+authors: mmassari
+tags:
+  - 2026-April
+  - 2026
+  - April
+---
+
+## Week 18 (April 29th – May 5th)
+
+- The `/packit test` command now supports testing with builds from multiple pull requests. You can specify multiple PRs using the format `/packit test namespace/repo#123 namespace/repo#456` or GitHub URLs, allowing you to combine artifacts from several PRs in a single test run. ([packit-service#3118](https://github.com/packit/packit-service/pull/3118))