Fix commit for isodate and adjust wording for debugging exercise

exercises/debugging-strategies.qmd

@@ -5,12 +5,12 @@ title: "Debugging strategies"
 ### 1. Approach on locating Python bugs
 
 _The tasks should be done using the test repository <https://github.com/gweis/isodate>,
-specifically commit 8856fdf0 (HEAD of `master` branch at the moment of writing this)._
+specifically version `v0.6.1` (commit `4f36d7e6f`)._
 
 _It is a Python library to parse date and times according to the ISO 8601 standard.
-Although it works great in many use cases, there are some documented bugs in the code.
+Although it works great in many use cases, there are some documented bugs in the code for former versions.
 But the linked repository was not chosen to cast a bad light on it in any way.
-In fact, it does a good job providing tests and stating which problems still occur in the code._
+In fact, it does a good job providing tests and stating which problems occured in the code._
 
 **Tasks**