Update README to remove tests badge (#729)

Removed tests badge from README as the test file no longer exists (things run through Garnix)

Author: thomashoneyman

README.md

@@ -1,6 +1,6 @@
 # PureScript Registry Development
 
-[![deploy](https://github.com/purescript/registry-dev/actions/workflows/deploy.yml/badge.svg)](https://github.com/purescript/registry-dev/actions/workflows/deploy.yml) [![tests](https://github.com/purescript/registry-dev/actions/workflows/main.yml/badge.svg)](https://github.com/purescript/registry-dev/actions/workflows/main.yml)
+[![deploy](https://github.com/purescript/registry-dev/actions/workflows/deploy.yml/badge.svg)](https://github.com/purescript/registry-dev/actions/workflows/deploy.yml)
 
 This repository hosts the code for the PureScript Registry and its affiliated projects. If you are new to the registry and are interested in its development, then the following should be helpful: