Fix gulp-mustache types (#25165)

* Fix gulp-mustache types

* Fix `gulp-mustache` test

types/gulp-mustache/gulp-mustache-tests.ts

@@ -4,6 +4,33 @@ import { Transform } from "stream";
 mustache({ // $ExpectType Transform
     msg: "Hello Gulp!"
 });
+mustache({
+  name: "Chris",
+  value: 10000,
+  taxed_value: 10000 - (10000 * 0.4),
+  in_ca: true
+});
+mustache({
+  repo: [
+    { name: "resque" },
+    { name: "hub" },
+    { name: "rip" }
+  ]
+});
+mustache({
+  name: "Willy",
+  wrapped: () => {
+    return (text: string, render: (arg: string) => string) => {
+      return `<b>${render(text)}</b>`;
+    };
+  }
+});
+mustache({
+  "person?": { name: "Jon" }
+});
+mustache({
+  repo: []
+});
 
 mustache({ // $ExpectType Transform
     msg: "Hello Gulp!",

types/gulp-mustache/index.d.ts

@@ -11,7 +11,7 @@ declare namespace GulpMustache {
     type View = Hash | string | undefined;
 
     interface Hash {
-        [key: string]: string;
+        [key: string]: any;
     }
 
     interface Options {