Fix typed issue

Author: cderv

src/core/temp-types.ts

@@ -9,5 +9,5 @@ export interface TempContext {
   createFile: (options?: Deno.MakeTempOptions) => string;
   createDir: (options?: Deno.MakeTempOptions) => string;
   cleanup: () => void;
-  onCleanup: (handler: VoidFunction) => VoidFunction[];
+  onCleanup: (handler: VoidFunction) => void;
 }

src/core/temp.ts

@@ -53,7 +53,7 @@ export function globalTempContext() {
   return tempContext;
 }
 
-export function createTempContext(options?: Deno.MakeTempOptions) {
+export function createTempContext(options?: Deno.MakeTempOptions): TempContext {
   let dir: string | undefined = Deno.makeTempDirSync({
     ...options,
     dir: tempDir,