Update dependency io.grpc:grpc-api to v1.81.0

Author: renovate-bot

appengine-api-1.0-sdk/pom.xml

@@ -30,7 +30,7 @@
     <dependency> <!-- needed for remote_api for opencensus. -->
       <groupId>io.grpc</groupId>
       <artifactId>grpc-api</artifactId>
-      <version>1.80.0</version>
+      <version>1.81.0</version>
        <optional>true</optional>
    </dependency>
     <dependency>