Bump grpc-java to 1.81.0 to silence Java 25 Unsafe deprecation warning

[ahmedmuhsin]

Why

Running the worker on Java 25 produces these warnings on startup:

WARNING: A terminally deprecated method in sun.misc.Unsafe has been called
WARNING: sun.misc.Unsafe::allocateMemory has been called by com.microsoft.azure.functions.shaded.io.grpc.netty.shaded.io.netty.util.internal.PlatformDependent0$2 (file:/.../azure-functions-java-worker.jar)
WARNING: Please consider reporting this to the maintainers of class com.microsoft.azure.functions.shaded.io.grpc.netty.shaded.io.netty.util.internal.PlatformDependent0$2
WARNING: sun.misc.Unsafe::allocateMemory will be removed in a future release

The warning comes from the shaded Netty inside grpc-netty-shaded (Netty 4.1.118.Final ships inside grpc-java 1.75.0). Netty 4.1.x calls the now terminally-deprecated sun.misc.Unsafe::allocateMemory for direct-buffer allocation; JDK 23+ flagged that method, and JDK 25 prints the warning on startup.

What

Bumps grpc.version from 1.75.0 → 1.81.0 (latest stable). That pulls in shaded Netty 4.1.132.Final, which routes direct-buffer allocation away from the deprecated method, so the warning disappears with no code or launch-argument changes.

	Before	After
grpc-java	1.75.0	1.81.0
shaded Netty	4.1.118.Final	4.1.132.Final

Java 8 compatibility

grpc-java 1.81.0 still targets Java 8 bytecode and ships with animal-sniffer checks intact (visible in the dependency tree), so this keeps the worker compatible with the full Java 8 → 25 range we support.

Verification

• mvn clean package -DskipTests succeeds; uber-jar correctly bundles grpc-*-1.81.0 and grpc-netty-shaded-1.81.0.
• mvn test: 63/63 tests pass, no regressions.
• Manual smoke run on Java 25 — the sun.misc.Unsafe::allocateMemory warning no longer appears.