Revert "Updating grpc"

This reverts commit 7d641dba15ff596c56007807eb9a89f710b66a09.
This breaks the grpc example.
diff --git a/parent/pom.xml b/parent/pom.xml
index bd0bbb2..0b1b784 100644
--- a/parent/pom.xml
+++ b/parent/pom.xml
@@ -241,7 +241,7 @@
         <google-truth-version>0.30</google-truth-version>
         <graphql-java-version>13.0</graphql-java-version>
         <grizzly-websockets-version>2.3.25</grizzly-websockets-version>
-        <grpc-version>1.25.0</grpc-version>
+        <grpc-version>1.24.1</grpc-version>
         <grpc-google-auth-library-version>0.13.0</grpc-google-auth-library-version>
         <grpc-guava-version>26.0-android</grpc-guava-version>
         <grpc-java-jwt-version>3.7.0</grpc-java-jwt-version>