Fix chrismas melody cmake file

Author: jcarranz97

tone/christmas_melody/CMakeLists.txt

@@ -1,12 +1,12 @@
-add_executable(pico_tone
-    pico_tone.c
+add_executable(christmas_melody
+    christmas_melody.c
 )
 
 # Add pico_stdlib library which aggregates commonly used features
-target_link_libraries(pico_tone pico_stdlib hardware_pwm)
+target_link_libraries(christmas_melody pico_stdlib pico_tone)
 
 # Create map/bin/hex/uf2 file in addition to ELF.
-pico_add_extra_outputs(pico_tone)
+pico_add_extra_outputs(christmas_melody)
 
 # add url via pico_set_program_url
-example_auto_set_url(pico_tone)
+example_auto_set_url(christmas_melody)