fix(core/cbor): set explicit return type to de-genericize alloc fn (#1676)

Author: kuhe

.changeset/swift-garlics-notice.md

@@ -0,0 +1,5 @@
+---
+"@smithy/core": patch
+---
+
+set explicit return type for cbor alloc

packages/core/src/submodules/cbor/cbor-types.ts

@@ -64,7 +64,7 @@ export const extendedFloat64 = 27; // 0b11011
 
 export const minorIndefinite = 31; // 0b11111
 
-export function alloc(size: number) {
+export function alloc(size: number): Uint8Array {
   return typeof Buffer !== "undefined" ? Buffer.alloc(size) : new Uint8Array(size);
 }