chore(deps): bump the grpc group with 6 updates (spiffe#427)

Bumps the grpc group with 6 updates:

| Package | From | To |
| --- | --- | --- |
| [io.grpc:grpc-protobuf](https://github.com/grpc/grpc-java) | `1.80.0` | `1.81.0` |
| [io.grpc:grpc-stub](https://github.com/grpc/grpc-java) | `1.80.0` | `1.81.0` |
| [io.grpc:grpc-inprocess](https://github.com/grpc/grpc-java) | `1.80.0` | `1.81.0` |
| [io.grpc:grpc-testing](https://github.com/grpc/grpc-java) | `1.80.0` | `1.81.0` |
| [io.grpc:grpc-netty-shaded](https://github.com/grpc/grpc-java) | `1.80.0` | `1.81.0` |
| [io.grpc:grpc-netty](https://github.com/grpc/grpc-java) | `1.80.0` | `1.81.0` |


Updates `io.grpc:grpc-protobuf` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-stub` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-inprocess` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-testing` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-netty-shaded` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-netty` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-stub` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-inprocess` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-testing` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-netty-shaded` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

Updates `io.grpc:grpc-netty` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

---
updated-dependencies:
- dependency-name: io.grpc:grpc-protobuf
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-stub
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-inprocess
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-testing
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-netty-shaded
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-netty
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-stub
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-inprocess
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-testing
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-netty-shaded
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
- dependency-name: io.grpc:grpc-netty
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: grpc
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

build.gradle

@@ -16,7 +16,7 @@ subprojects {
     version = project.version
 
     ext {
-        grpcVersion = '1.80.0'
+        grpcVersion = '1.81.0'
         jupiterVersion = '5.13.4'
         mockitoVersion = '4.11.0'
         nimbusVersion = '10.9'