[Deps] Pin axe-core version

Pin axe-core to v3.4.1 which is the latest version in which tests for the 'autocomplete-valid' rule pass.

See #665 and dequelabs/axe-core#2060 for more information and small discussion.

package.json

@@ -62,7 +62,7 @@
     "aria-query": "^4.0.1",
     "array-includes": "^3.0.3",
     "ast-types-flow": "^0.0.7",
-    "axe-core": "^3.4.0",
+    "axe-core": "=3.4.1",
     "axobject-query": "^2.1.1",
     "damerau-levenshtein": "^1.0.4",
     "emoji-regex": "^7.0.2",