v9.0.0

• #60, #64, #68, #69, #70 - new TFM, modernization, tidy-up (@KodrAus, @nblumhardt)
• #61 - expose enrichment through ILoggingBuilder (@KodrAus)
• #65 - fix EventId override (@KodrAus)
• #67 - reject events with LogLevel.None (@chrisbbe)