added OpenSSF badge (#484)

## Description, Context and related Issue
adds OpenSSF badge to the README. This gives insight to the
sustainability of the project and enhances points of fair-software badge

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Please link to the issue here: -->
Refs #483 

## How Has This Been Tested?
README viewed in branch

## Types of changes
<!--- What types of changes does your code introduce? Please DELETE
options that are not relevant. -->
- New feature (non-breaking change which adds functionality)
- Improvement

## Overview
<!--- Go over all the following points, and DELETE options that are not
relevant. -->
- I have performed a self-review of my code, according to the [style
guide](https://github.com/Edirom/Edirom-Online/blob/develop/STYLE-GUIDE.md)
- I have read the
[CONTRIBUTING](https://github.com/Edirom/Edirom-Online/blob/develop/CONTRIBUTING.md)
document.

README.md

@@ -5,6 +5,7 @@
 [![Contributor Covenant](https://img.shields.io/badge/Contributor%20Covenant-2.1-4baaaa.svg)](CODE_OF_CONDUCT.md)
 [![GitHub release](https://img.shields.io/github/v/release/Edirom/Edirom-Online.svg)](https://github.com/Edirom/Edirom-Online/releases) 
 [![FAIR checklist badge](https://fairsoftwarechecklist.net/badge.svg)](https://fairsoftwarechecklist.net/v0.2?f=31&a=32113&i=32300&r=133) 
+[![OpenSSF Best Practices](https://www.bestpractices.dev/projects/9746/badge)](https://www.bestpractices.dev/projects/9746)
 [![fair-software.eu](https://img.shields.io/badge/fair--software.eu-%E2%97%8F%20%20%E2%97%8F%20%20%E2%97%8B%20%20%E2%97%8B%20%20%E2%97%8B-orange)](https://fair-software.eu)
 [![DOI](https://zenodo.org/badge/5966814.svg)](https://zenodo.org/badge/latestdoi/5966814)