remove travis-ci badge
||Badges|
|---|---|
|AppVeyor|[![AppVeyor build status](https://ci.appveyor.com/api/projects/status/github/softethervpn/softethervpn?branch=master&svg=true)](https://ci.appveyor.com/project/softethervpn/softethervpn) |
-|Travis CI|[![Travis CI build status](https://travis-ci.org/SoftEtherVPN/SoftEtherVPN.svg?branch=master)](https://travis-ci.org/SoftEtherVPN/SoftEtherVPN) |
|GitLab CI|[![GitLab CI build status](https://gitlab.com/SoftEther/SoftEtherVPN/badges/master/pipeline.svg)](https://gitlab.com/SoftEther/SoftEtherVPN/pipelines)|
|Coverity Scan|[![Coverity Scan build status](https://scan.coverity.com/projects/16304/badge.svg)](https://scan.coverity.com/projects/softethervpn-softethervpn)|
|Azure Pipelines|[![Azure Pipelines build status for Nightly](https://dev.azure.com/SoftEther-VPN/SoftEther%20VPN/_apis/build/status/6?api-version=6.0-preview.1)](https://dev.azure.com/SoftEther-VPN/SoftEther%20VPN/_build?definitionId=6)|
