Pin microshift build for openshift-4.18 rc.4 (#5977)

Created by job run https://art-jenkins.apps.prod-stable-spoke1-dc-iad2.itup.redhat.com/job/aos-cd-builds/job/build%252Fbuild-microshift/1594

Co-authored-by: AOS Automation Release Team <[email protected]>

releases.yml

@@ -19,7 +19,12 @@ releases:
         upgrades: 4.17.11,4.17.12,4.18.0-ec.3,4.18.0-ec.4,4.18.0-rc.0,4.18.0-rc.1,4.18.0-rc.2,4.18.0-rc.3
       members:
         images: []
-        rpms: []
+        rpms:
+          - distgit_key: microshift
+            why: Pin microshift to assembly
+            metadata:
+              is:
+                el9: microshift-4.18.0~rc.4-202501101507.p0.g207dbb3.assembly.rc.4.el9
       rhcos:
         rhel-coreos:
           images: