fix: add npm funding link

Author: mattlewis92

package.json

@@ -2,6 +2,9 @@
   "name": "karma-coverage-istanbul-reporter",
   "version": "2.1.0",
   "description": "A karma reporter that uses the latest istanbul 1.x APIs (with full sourcemap support) to report coverage.",
+  "funding": {
+    "url": "https://github.com/sponsors/mattlewis92"
+  },
   "main": "src/reporter.js",
   "files": [
     "src"