Add os and python 3.10 to github build workflow

Author: cffls

.github/workflows/main.yml

@@ -10,10 +10,11 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: [3.7, 3.8, 3.9]
+        os: [ubuntu-latest, macos-latest]
+        python-version: [3.7, 3.8, 3.9, '3.10']
 
     steps:
       - uses: actions/checkout@v2

README.md

@@ -4,6 +4,10 @@
 [![codecov](https://codecov.io/gh/cffls/pycardano/branch/main/graph/badge.svg?token=62N0IL9IMQ)](https://codecov.io/gh/cffls/pycardano)
 [![Documentation Status](https://readthedocs.org/projects/pycardano/badge/?version=latest)](https://pycardano.readthedocs.io/en/latest/?badge=latest)
 
+[![Linux](https://svgshare.com/i/Zhy.svg)](https://svgshare.com/i/Zhy.svg)
+[![macOS](https://svgshare.com/i/ZjP.svg)](https://svgshare.com/i/ZjP.svg)
+
+
 PyCardano is a Cardano library written in Python. It allows users to create and sign transactions without 
 depending on third-party Cardano serialization tools, such as
 [cardano-cli](https://github.com/input-output-hk/cardano-node#cardano-cli) and