ci: Add test workflow status badge

Author: dhl

.github/workflows/test.yml

@@ -1,10 +1,10 @@
-name: Run tests and upload coverage
+name: Tests and Coverage
 
 on:
   push
 
 jobs:
-  coverage:
+  test:
     name: Report coverage
     runs-on: ubuntu-latest
     steps:

README.md

@@ -1,5 +1,6 @@
 # blake2b-solidity
 
+![tests and coverage](https://github.com/dhl/blake2b-solidity/actions/workflows/test.yml/badge.svg)
 [![codecov](https://codecov.io/github/dhl/blake2b-solidity/graph/badge.svg?token=4WOC5GEC7H)](https://codecov.io/github/dhl/blake2b-solidity)
 
 `blake2b-solidity` is a high-performance Solidity implementation of the [BLAKE2b](https://www.blake2.net/) hash