Adds properly licneced sounds back to the Pig and the Cow (#29465)

* Pig and Cow are now no longer silent

* Added attribution to attributions.txt

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Signed-off-by: Burzah <116982774+Burzah@users.noreply.github.com>
Co-authored-by: Burzah <116982774+Burzah@users.noreply.github.com>

code/modules/mob/living/basic/farm_animals/cow.dm

@@ -2,6 +2,7 @@
 	speech_chance = 2
 	speak = list("Moo?", "Moo", "MOOOOOO")
 	speak_verbs = list("moos", "moos hauntingly")
+	sound = list('sound/creatures/cow.ogg')
 	emote_hear = list("brays.")
 	emote_see = list("shakes her head.")
 

code/modules/mob/living/basic/farm_animals/pig.dm

@@ -1,6 +1,7 @@
 /datum/ai_planning_subtree/random_speech/pig
 	speech_chance = 2
 	speak = list("oink?", "oink", "OINK")
+	sound = list('sound/creatures/pig.ogg')
 	emote_hear = list("oinks.")
 	emote_see = list("rolls around.")