v1.18.0

Changes:

• Add log messages to GroupBy operations
• Warn users about ill-formed date/time strings
• Prevent segfault when formatting null strings
• Drop Python 3.9
• Add error handler for log formatting
• Better error handling in groupby functions
• Fix GetNextWorkIndex and callers
• Set sdsfile_test gtest discovery timeout
• Add thread wakeup test
• Add benchmarks for GroupBy operations