Ignore frequent icon finder problem

This seems to be only a problem on GitHub (actions)?
Adding a target for the credits anyway.

Author: ascheman

self-check/build.gradle

@@ -7,7 +7,8 @@ htmlSanityCheck {
 
     checkingResultsDir = file("../build/reports/htmlchecks")
     excludes = [
-            "https://www.baeldung.com/.*" // Baeldung seems to have implemented some anti-robot/GPT strategy?
+            "https://www.baeldung.com/.*", // Baeldung seems to have implemented some anti-robot/GPT strategy?
+            "https://www.iconfinder.com/icons/118743/arrow_up_icon", // This fails frequently on GitHub pages
     ]
 
     httpSuccessCodes = [ 429 ]

src/docs/arc42/chapters/chap-08-Concepts.adoc

@@ -94,6 +94,7 @@ The appropriate copy method took a https://github.com/gradle/gradle/blob/5c45052
 
 
 ==== Attributions
-Credits for the arrow-icon https://www.iconfinder.com/icons/118743/arrow_up_icon
+
+Credits for the https://www.iconfinder.com/icons/118743/arrow_up_icon[arrow up icon] go to https://www.freepik.com/[FreeP!K].