Update .github/workflows/test-software.eessi.io.yml

Co-authored-by: Caspar van Leeuwen <33718780+casparvl@users.noreply.github.com>

Author: TopRichard

.github/workflows/test-software.eessi.io.yml

@@ -62,8 +62,12 @@ jobs:
           EESSI_VERSIONS=""
           
           # Check for specific versions in the changed easystack files
+          # The regex pattern matches a prefix, but only returns the part after \K, so that we get only the version
+          # The sort ensures predictable ordering, and with -u only keeps unique items (neither are probably essential, but both are nice)
+          # Finally, since the grep returns multiple lines if there are multiple versions that were touched,
+          # the tr replaces newlies with space, to make this space-separated.          
           EESSI_VERSIONS=$(git diff --name-only origin/${{ github.base_ref }}...HEAD \
-            | grep -oP 'easystacks/software\.eessi\.io/\K[0-9]{4}\.[0-9]{2}' \
+            | grep -oP 'easystacks/software\.eessi\.io/\K[0-9]+\.[0-9]+' \
             | sort -u \
             | tr '\n' ' ')
           echo "PR easystack changes related to EESSI VERSION: $EESSI_VERSIONS"