Add bomr exclusion for the maven shade plugin

Closes gh-21265

Author: snicoll

.bomr/bomr.yaml

@@ -12,6 +12,10 @@ bomr:
         versions:
           # 10.15 requires Java 9
           - '[10.15,)'
+      - project: maven-shade-plugin
+        versions:
+          # https://github.com/spring-projects/spring-boot/issues/21128
+          - '[3.2.3,)'
   verify:
     ignored-dependencies:
       # Avoid conflicting transitive requirements for