add GSL as a dependency

src/CMakeLists.txt

@@ -33,7 +33,7 @@ ADD_LIBRARY(
 
 # define the dependencies
 TARGET_INCLUDE_DIRECTORIES(ArrivalMANager INTERFACE EuroScope)
-TARGET_LINK_LIBRARIES(ArrivalMANager EuroScope)
+TARGET_LINK_LIBRARIES(ArrivalMANager EuroScope GSL)
 
 # configure the debugger and update the linker flags
 IF(MSVC)