Bump default version to latest (0.18.0) (#269)

Author: trask

action.yml

@@ -28,7 +28,7 @@ inputs:
     required: false
   lycheeVersion:
     description: "Use custom version of lychee link checker"
-    default: v0.17.0
+    default: v0.18.0
     required: false
   output:
     description: "Summary output file path"