Update dependency ava to v6

Author: renovate[bot]

package.json

@@ -91,7 +91,7 @@
     "@babel/polyfill": "7.12.1",
     "@babel/preset-env": "7.13.10",
     "@babel/register": "7.13.8",
-    "ava": "3.15.0",
+    "ava": "6.4.1",
     "babel-plugin-transform-remove-console": "6.9.4",
     "babel-plugin-unassert": "3.0.1",
     "babel-preset-power-assert": "3.0.0",