Add GitHub Actions badge to README (#449)

* Update README.md

Signed-off-by: Josh Branham <josh.php@gmail.com>

* Update README.md

Signed-off-by: Josh Branham <josh.php@gmail.com>

---------

Signed-off-by: Josh Branham <josh.php@gmail.com>

README.md

@@ -1,6 +1,6 @@
 # attr_encrypted
 
-[![Build Status](https://app.travis-ci.com/attr-encrypted/attr_encrypted.svg?branch=master)](https://travis-ci.org/attr-encrypted/attr_encrypted) [![Test Coverage](https://codeclimate.com/github/attr-encrypted/attr_encrypted/badges/coverage.svg)](https://codeclimate.com/github/attr-encrypted/attr_encrypted/coverage) [![Code Climate](https://codeclimate.com/github/attr-encrypted/attr_encrypted/badges/gpa.svg)](https://codeclimate.com/github/attr-encrypted/attr_encrypted) [![Gem Version](https://badge.fury.io/rb/attr_encrypted.svg)](https://badge.fury.io/rb/attr_encrypted)
+![workflow](https://github.com/attr-encrypted/attr_encrypted/actions/workflows/CI.yml/badge.svg) [![Gem Version](https://badge.fury.io/rb/attr_encrypted.svg)](https://badge.fury.io/rb/attr_encrypted)
 
 Generates attr_accessors that transparently encrypt and decrypt attributes.