Add test support for Rocky Linux 9.3 (Blue Onyx)

Adds test resources and test case for Rocky Linux 9.3, a stable RHEL
clone with support until 2032. Includes rocky-release files, upstream
attribution, CPE metadata, and os-release for proper distribution
identification.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: nir0s

tests/resources/distros/rocky9/etc/rocky-release

@@ -0,0 +1 @@
+Rocky Linux release 9.3 (Blue Onyx)

tests/resources/distros/rocky9/etc/rocky-release-upstream

@@ -0,0 +1 @@
+Derived from Red Hat Enterprise Linux 9.3

tests/resources/distros/rocky9/etc/system-release-cpe

@@ -0,0 +1 @@
+cpe:/o:rocky:rocky:9::baseos

tests/resources/distros/rocky9/usr/lib/os-release

@@ -0,0 +1,17 @@
+NAME="Rocky Linux"
+VERSION="9.3 (Blue Onyx)"
+ID="rocky"
+ID_LIKE="rhel centos fedora"
+VERSION_ID="9.3"
+PLATFORM_ID="platform:el9"
+PRETTY_NAME="Rocky Linux 9.3 (Blue Onyx)"
+ANSI_COLOR="0;32"
+LOGO="fedora-logo-icon"
+CPE_NAME="cpe:/o:rocky:rocky:9::baseos"
+HOME_URL="https://rockylinux.org/"
+BUG_REPORT_URL="https://bugs.rockylinux.org/"
+SUPPORT_END="2032-05-31"
+ROCKY_SUPPORT_PRODUCT="Rocky-Linux-9"
+ROCKY_SUPPORT_PRODUCT_VERSION="9.3"
+REDHAT_SUPPORT_PRODUCT="Rocky Linux"
+REDHAT_SUPPORT_PRODUCT_VERSION="9.3"

tests/test_distro.py

@@ -451,6 +451,19 @@ def test_almalinux10_os_release(self) -> None:
         }
         self._test_outcome(desired_outcome)
 
+    def test_rocky9_os_release(self) -> None:
+        desired_outcome = {
+            "id": "rocky",
+            "name": "Rocky Linux",
+            "pretty_name": "Rocky Linux 9.3 (Blue Onyx)",
+            "version": "9.3",
+            "pretty_version": "9.3 (Blue Onyx)",
+            "best_version": "9.3",
+            "like": "rhel centos fedora",
+            "codename": "Blue Onyx",
+        }
+        self._test_outcome(desired_outcome)
+
     def test_slackware14_os_release(self) -> None:
         desired_outcome = {
             "id": "slackware",