Update dependency portfinder to v1.0.26 (#579)

Co-authored-by: Renovate Bot <[email protected]>

Author: renovate[bot]

package-lock.json

@@ -50,7 +50,7 @@
     "mkdirp": "1.0.4",
     "mocha": "7.1.2",
     "mocha-lcov-reporter": "1.3.0",
-    "portfinder": "1.0.25",
+    "portfinder": "1.0.26",
     "selenium-assistant": "5.4.0",
     "sinon": "7.5.0",
     "which": "2.0.2"