update travis badge to point to actions status (apache#219)

* update travis badge to point to actions status

It seems Travis is currently not updating as expected, likely as a side effect of the repo moving. If we're comfortable leaning on Actions, then we can switch out the badge here and plan to remove Travis entirely. Alternatively we could reconfigure Travis to work with the new repo name.

* Refer to correct branch

Co-authored-by: Dandandan <danielheres@gmail.com>

Author: maxcountryman

README.md

@@ -2,7 +2,7 @@
 
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 [![Version](https://img.shields.io/crates/v/sqlparser.svg)](https://crates.io/crates/sqlparser)
-[![Build Status](https://travis-ci.org/ballista-compute/sqlparser-rs.svg?branch=main)](https://travis-ci.org/ballista-computee/sqlparser-rs)
+[![Build Status](https://github.com/ballista-compute/sqlparser-rs/workflows/Rust/badge.svg?branch=main)](https://github.com/ballista-compute/sqlparser-rs/actions?query=workflow%3ARust+branch%3Amain)
 [![Coverage Status](https://coveralls.io/repos/github/ballista-compute/sqlparser-rs/badge.svg?branch=main)](https://coveralls.io/github/ballista-compute/sqlparser-rs?branch=main)
 [![Gitter Chat](https://badges.gitter.im/sqlparser-rs/community.svg)](https://gitter.im/sqlparser-rs/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)