CPASAnimState: Make use of size_t for GetAnimParmData()

Given the rest of the interface now uses size_t, we can convert this
over. While we're at it, we can also take the result of the at() call
inside of it in order to avoid any copies of data altogether.

Runtime/Character/CPASAnimState.hpp

@@ -27,7 +27,7 @@ public:
   explicit CPASAnimState(int stateId);
   s32 GetStateId() const { return x0_id; }
   s32 GetNumAnims() const { return x14_anims.size(); }
-  CPASAnimParm GetAnimParmData(s32 animId, u32 parmIdx) const;
+  CPASAnimParm GetAnimParmData(s32 animId, size_t parmIdx) const;
   std::pair<float, s32> FindBestAnimation(const rstl::reserved_vector<CPASAnimParm, 8>& parms, CRandom16& rand,
                                           s32 ignoreAnim) const;
 };