Fix: Remove prune workflow

Author: localheinz

.github/CONTRIBUTING.md

@@ -5,7 +5,6 @@ We are using [GitHub Actions](https://github.com/features/actions) as a continuo
 For details, take a look at the following workflow configuration files:
 
 - [`workflows/integrate.yaml`](workflows/integrate.yaml)
-- [`workflows/prune.yaml`](workflows/prune.yaml)
 - [`workflows/release.yaml`](workflows/release.yaml)
 - [`workflows/triage.yaml`](workflows/triage.yaml)
 

.github/workflows/prune.yaml

@@ -1,7 +1,6 @@
 # diff
 
 [![Integrate](https://github.com/localheinz/diff/workflows/Integrate/badge.svg?branch=main)](https://github.com/localheinz/diff/actions)
-[![Prune](https://github.com/localheinz/diff/workflows/Prune/badge.svg?branch=main)](https://github.com/localheinz/diff/actions)
 [![Release](https://github.com/localheinz/diff/workflows/Release/badge.svg?branch=main)](https://github.com/localheinz/diff/actions)
 
 [![Code Coverage](https://codecov.io/gh/localheinz/diff/branch/main/graph/badge.svg)](https://codecov.io/gh/localheinz/diff)