Miniflux 2.0.6

• Improve graceful shutdown
• Simplify Heroku deployment
• Display memory usage and some metrics in logs
• Increase read/write timeout for HTTP server
• Add support for Dublin Core date in RDF feeds
• Do not return an error if the user session is not found
• Handle some non-english date formats
• Rename RSS parser getters
• Get the right comments URL when having multiple namespaces
• Ignore caching headers for feeds that send "Expires: 0"
• Update translations