zts-report: don't crash on non-UTF-8 chars in the log

The report generator expects the log to be clean and tidy UTF-8. That
can be a problem if you use some of the verbose/debug test runner
options, which sends all sorts of weird output from arbitrary programs
to the log.

This just makes Python a little more relaxed about such things. It
shouldn't matter in practice, as those lines didn't match the test
result regex anyway, and are discarded immediately.

Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/

tests/test-runner/bin/zts-report.py.in

@@ -389,7 +389,7 @@ if os.environ.get('CI') == 'true':
 
 def process_results(pathname):
     try:
-        f = open(pathname)
+        f = open(pathname, errors='replace')
     except IOError as e:
         print('Error opening file:', e)
         sys.exit(1)