remove Philipps Email, as it does not work anymore and we don't (yet?) have permission to use another

Author: knarrff

contributors.yml

@@ -142,7 +142,6 @@ authors:
       - name: Competence Center Digital Research, Friedrich Schiller University Jena, Germany
         ror: https://ror.org/05qpz1x62
     orcid: 0000-0003-3931-6670
-    email: philipp.matthias.schaefer@uni-jena.de
     tier: 1
 
   - author: "Uwe Schmitt"