Bump com.azure:azure-core-http-netty in /plugins/repository-azure

Bumps [com.azure:azure-core-http-netty](https://github.com/Azure/azure-sdk-for-java) from 1.12.8 to 1.13.8.
- [Release notes](https://github.com/Azure/azure-sdk-for-java/releases)
- [Commits](Azure/azure-sdk-for-java@azure-core-http-netty_1.12.8...azure-core-http-netty_1.13.8)

---
updated-dependencies:
- dependency-name: com.azure:azure-core-http-netty
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

plugins/repository-azure/build.gradle

@@ -47,7 +47,7 @@ dependencies {
   api 'com.azure:azure-core:1.39.0'
   api 'com.azure:azure-json:1.0.1'
   api 'com.azure:azure-storage-common:12.21.2'
-  api 'com.azure:azure-core-http-netty:1.12.8'
+  api 'com.azure:azure-core-http-netty:1.13.8'
   api "io.netty:netty-codec-dns:${versions.netty}"
   api "io.netty:netty-codec-socks:${versions.netty}"
   api "io.netty:netty-codec-http2:${versions.netty}"