ktest: Fix the month in the name of the failure directory

The Perl localtime() function returns the month starting at 0 not 1. This
caused the date produced to create the directory for saving files of a
failed run to have the month off by one.

  machine-test-useconfig-fail-20260314073628

The above happened in April, not March. The correct name should have been:

  machine-test-useconfig-fail-20260414073628

This was somewhat confusing.

Cc: stable@vger.kernel.org
Cc: John 'Warthog9' Hawley <warthog9@kernel.org>
Link: https://patch.msgid.link/20260420142426.33ad0293@fedora
Fixes: 7faafbd ("ktest: Add open and close console and start stop monitor")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Author: rostedt

tools/testing/ktest/ktest.pl

@@ -1855,7 +1855,7 @@ sub save_logs {
     my ($result, $basedir) = @_;
     my @t = localtime;
     my $date = sprintf "%04d%02d%02d%02d%02d%02d",
-	1900+$t[5],$t[4],$t[3],$t[2],$t[1],$t[0];
+	1900+$t[5],$t[4]+1,$t[3],$t[2],$t[1],$t[0];
 
     my $type = $build_type;
     if ($type =~ /useconfig/) {