test-avrdude: Adapt version check to new version format

The output of the version information in "avrdude -v" has changed between
avrdude 7.3 and now (commit cf0822b):

avrdude: Version 7.3

Avrdude version 7.3-20240814 (250a663a)

This means that the old grep call looking for "Version" cannot
find anything any more, and therefore needs to be changed.

This was not discovered as the test-avrdude script neglected to
abort if no version information is found.

tools/test-avrdude

@@ -150,7 +150,7 @@ fi
 arraylength=${#pgm_and_target[@]}
 type "$avrdude_bin" >/dev/null 2>&1 || { echo "$progname: cannot execute $avrdude_bin"; exit 1; }
 echo -n "Testing $avrdude_bin"
-$avrdude_bin -v 2>&1 | grep Version | cut -f2- -d: | sed s/Version/version/
+$avrdude_bin -v 2>&1 | grep '[vV]ersion' | cut -f2- -d: | sed s/Version/version/
 
 [[ -d $tmp && -w $tmp ]] || tmp=/tmp # Fall back to /tmp if tmp directory unusable
 status=$(mktemp "$tmp/$progname.status.XXXXXX")