fix(package): include tests folder

This is needed if you want to extend the buildserver and reuse tests

Author: felixfbecker

.gitattributes

@@ -3,7 +3,6 @@
 /.vscode export-ignore
 /fixtures export-ignore
 /images export-ignore
-/tests export-ignore
 /validation export-ignore
 /.dockerignore export-ignore
 /.editorconfig export-ignore