Add explicit export for ./* (#2413)

Author: ntkme

package.json

@@ -118,8 +118,11 @@
   "main": "./lib/sinon.js",
   "module": "./pkg/sinon-esm.js",
   "exports": {
-    "require": "./lib/sinon.js",
-    "import": "./pkg/sinon-esm.js"
+    ".": {
+      "require": "./lib/sinon.js",
+      "import": "./pkg/sinon-esm.js"
+    },
+    "./*": "./*"
   },
   "type": "module",
   "cdn": "./pkg/sinon.js",