VER: Release 0.7.0 - Githubissues

Document cancellation safety of LiveClient methods (credit: @yongqli)
Document live::Subscription::start is based on ts_event
Allow constructing a DateRange and DateTimeRange with an end based on a time::Duration
Implemented Debug for LiveClient, LiveClientBuilder, HistoricalClient, HistoricalClientBuilder, BatchClient, MetadataClient, SymbologyClient, and TimeseriesClient
Derived Clone for LiveClientBuilder and HistoricalClientBuilder
Added ApiKey type for safely deriving Debug for types containing an API key

Changed default upgrade_policy in LiveBuilder and GetRangeParams to Upgrade so by default the primary record types can always be used
Simplify DateRange and DateTimeRange by removing FwdFill variant that didn't work correctly

databento / databento-rs