chore: ignore changes in grpc showcase

Author: diegomarquezp

java-showcase/grpc-gapic-showcase-v1beta1/clirr-ignored-differences.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<differences>
+  <difference>
+    <differenceType>7012</differenceType>
+    <className>com/google/showcase/v1beta1/EchoGrpc$AsyncService</className>
+    <method>*failEchoWithDetails(*)</method>
+  </difference>
+</differences>