Clean up /scip-dotnet directory after building the binary

Author: olafurpg

Dockerfile

@@ -3,4 +3,5 @@ WORKDIR /scip-dotnet
 ADD . /scip-dotnet
 RUN dotnet pack
 ENV PATH="/root/.dotnet/tools:${PATH}"
-RUN dotnet tool install --add-source ScipDotnet/bin/Debug/ --global scip-dotnet
+RUN dotnet tool install --add-source ScipDotnet/bin/Debug/ --global scip-dotnet
+RUN rm -rf /scip-dotnet