* Bump up gRPC/protobuf to fix CVE-2021-2256

Upgrade to the latest grpc-java 1.42.1 which is only compatible and [tested against](https://github.com/grpc/grpc-java/pull/8551#discussion_r714182190) 3.17.2, but we can assume that 3.17.3 (which has osx-aarch_64 compatible maven artifacts) is save to use.

We could have also upgrade to the latest grpc-java 1.42.1 and latest protoc 3.19.1, but it can not be directly done, it needs to tweak the grpcs-java internal dependencies. So we choose the safest option and discarded this option because of the following reasons:
 - Protoc 3.19.1 generates code that relies on methods not available in protobuf-java 3.17.2 ([“issue”](https://github.com/protocolbuffers/protobuf/issues/9236#issue-1059594027)) (which java-grpc relies on). So we need to tell grpc-java via dependency management to use 3.19.1 instead of 3.17.2.
Signed-off-by: NMarc Navarro Sonnenfeld <marcnavarro@tetrate.io>

* [maven-release-plugin] prepare release v8.8.0

* [maven-release-plugin] prepare for next development iteration

* Create changes-8.8.0.md

* Reset changelog for 8.9.0

* Remove agent codes and clean up

* [maven-release-plugin] prepare release v8.7.0

* [maven-release-plugin] prepare for next development iteration

* [maven-release-plugin] prepare release v8.4.0

* [maven-release-plugin] prepare for next development iteration

* [maven-release-plugin] prepare release v8.3.0

* [maven-release-plugin] prepare for next development iteration

* [maven-release-plugin] prepare release v8.2.0

* [maven-release-plugin] prepare for next development iteration

* Upgrade dependencies and make the JDK11 compiling passed.

* Update license and fix license check file.

* Add CI for JDK11 compiling.

* Update doc.

* Add a muse configuration file

A muse configuration and file is necessary to educate the MuseDev CI
system on how to build Skywalking.

* Exclude .muse/* files from license check

* support build single module

* enforce maven version must greater than 3.6

* update build doc to support maven3.6+

* [maven-release-plugin] prepare release v8.1.0

* [maven-release-plugin] prepare for next development iteration

Signed-off-by: NGao Hongtao <hanahmily@gmail.com>

* [maven-release-plugin] prepare release v8.0.0

* [maven-release-plugin] prepare for next development iteration

* Remove all shardingsphere cases.