🤖 chore: Use c8 instead of nyc.

These changes were automatically generated by a transform whose code can be found at:
  - https://github.com/make-github-pseudonymous-again/rejuvenate/blob/a44c42967442d65fd14272682fb84a6f32feb841/src/transforms/coverage:replace-nyc-by-c8.js
Please contact the author of the transform if you believe there was an error.

package.json

@@ -26,7 +26,7 @@
   ],
   "scripts": {
     "build": "babel src -d lib",
-    "cover": "nyc --reporter=lcov npm test",
+    "cover": "c8 --all --src src --reporter=lcov npm test",
     "esdoc": "esdoc",
     "lint-config": "fixpack --dryRun",
     "lint-config-and-fix": "fixpack || fixpack",
@@ -43,15 +43,15 @@
     "@babel/register": "7.13.8",
     "@heap-data-structure/specification": "16.0.0",
     "ava": "3.15.0",
+    "c8": "7.7.3",
     "coveralls": "3.1.0",
     "esdoc": "1.1.0",
     "esdoc-ecmascript-proposal-plugin": "1.0.0",
     "esdoc-inject-script-plugin": "1.0.0",
     "esdoc-inject-style-plugin": "1.0.0",
     "esdoc-standard-plugin": "1.0.0",
     "fixpack": "4.0.0",
-    "np": "6.5.0",
-    "nyc": "15.1.0"
+    "np": "6.5.0"
   },
   "ava": {
     "files": [