[fix] Revert Dockerfile change

Author: CodingWithSaksham

Dockerfile

@@ -28,7 +28,7 @@ RUN apt-get update && \
   shared-mime-info \
   && rm -rf /var/lib/apt/lists/*
 
-WORKDIR /opt/openwisp/tests
+WORKDIR /opt/openwisp
 
 # Install test requirements first so this layer is cached separately
 # from the source code copy below.