chore: remove the supporting of EOL OS ubuntu 16.04 (#1553)

#1348

Benifits:
- Updating the list of OS versions we would test and support, including adding
   newer OS versions and removing EOL OS versions
- A first step towards supporting C++17 which need higher version of GCC

Although we drop the supporting of Ubuntu 16.04, Pegasus developers and
users are still able to build and run Pegasus themselves.

.github/workflows/build-push-env-docker.yml

@@ -39,7 +39,6 @@ jobs:
       fail-fast: false
       matrix:
         dockertag:
-          - ubuntu1604
           - ubuntu1804
           - ubuntu2004
           - ubuntu2204

.github/workflows/regular-build.yml

@@ -52,7 +52,6 @@ jobs:
       fail-fast: false
       matrix:
         os:
-          - ubuntu1604
           - ubuntu1804
           - ubuntu2004
           - ubuntu2204

.github/workflows/thirdparty-regular-push.yml

@@ -71,7 +71,6 @@ jobs:
       fail-fast: false
       matrix:
         osversion:
-          - ubuntu1604
           - ubuntu1804
           - ubuntu2004
           - ubuntu2204
@@ -109,7 +108,6 @@ jobs:
       fail-fast: false
       matrix:
         osversion:
-          - ubuntu1604
           - ubuntu1804
           - ubuntu2004
           - ubuntu2204

docker/README.md

@@ -36,7 +36,6 @@ Building environment for Pegasus compilation.
 Github Actions automatically rebuilds and publishes build-env for every commit.
 
 - `apache/pegasus:build-env-centos7`
-- `apache/pegasus:build-env-ubuntu1604`
 - `apache/pegasus:build-env-ubuntu1804`
 - `apache/pegasus:build-env-ubuntu2004`
 - `apache/pegasus:build-env-ubuntu2204`
@@ -60,7 +59,6 @@ This is a Docker image for Pegasus unit-testing. It prebuilts the thirdparty lib
 so jobs based on this image can skip building third-parties.
 
 - `apache/pegasus:thirdparties-bin-centos7-master`
-- `apache/pegasus:thirdparties-bin-ubuntu1604-master`
 - `apache/pegasus:thirdparties-bin-ubuntu1804-master`
 - `apache/pegasus:thirdparties-bin-ubuntu2004-master`
 - `apache/pegasus:thirdparties-bin-ubuntu2204-master`