Remove Heroku logo from README

Removed Heroku sponsorship logo from README.

Author: wurstbrot

README.md

@@ -183,8 +183,6 @@ Multilanguage support is not given currently and not planned.
 
 [![Apprio Inc](https://github.com/wurstbrot/DevSecOps-MaturityModel/raw/master-old/assets/images/Apiiro_black_logo.png)](https://apiiro.com/)
 
-[![Heroku (hosting)](https://github.com/wurstbrot/DevSecOps-MaturityModel/raw/main/src/assets/images/sponsors/heroku.png)](https://www.heroku.com/open-source-credit-program)
-
 # Donations
 
 If you are using the model or you are inspired by it, want to help but don't want to create pull requests? You can donate at the [OWASP Project Wiki Page](https://owasp.org/donate/?reponame=www-project-devsecops-maturity-model&title=OWASP+Devsecops+Maturity+Model). Donations might be used for the design of logos/images/design or travels.