Merge pull request #7 from serlo/remove-zero-install

chore: Remove yarn zero-install

Author: kulla

.gitignore

@@ -1,8 +1,8 @@
 /node_modules/
 
-# Yarn (with Zero-Installs)
+# Yarn (without zero-installs)
+.pnp.*
 .yarn/*
-!.yarn/cache
 !.yarn/patches
 !.yarn/plugins
 !.yarn/releases