Release 0.3.0

fix booleans not recognized in a pg table

Update goreleaser config to remove deprecations

Add support for InfluxDB retention policies

Because of the behaviour of the InfluxDB query
'SHOW MEASUREMENTS' where it is not specified which measurements
belong to which retention policy, it was impossible to extract
a measure from other than the default RP. This commit removes a
redundant check for the presence of a measurement when doing
migration of a single measurement and modifies the generated
influx queries for schema exploration in order to properly select
a measurement in a specified RP. Passing the name of the measurement
as "retention_policy"."measurement name" now exports the proper data

Initial release