Fix ep3 cmakelist to point to correct test dir

Author: connoraird

episodes/3-fortran-unit-test-syntax/challenge/CMakeLists.txt

@@ -14,4 +14,4 @@ file(GLOB PROJ_SRC_FILES "${PROJECT_SOURCE_DIR}/src/*.f90")
 # Build src executables
 add_executable("${PROJECT_NAME}" "${PROJ_SRC_FILES}")
 
-add_subdirectory("test/pfunit")
+add_subdirectory("test")