Fix spec for ruby-head
Fix spec for ruby-head

Encoding "~" in 2.5 via `CGI.escape` will not do anything. In
Ruby <= 2.4, this returns "%7E".
mvz/influxdb-ruby,influxdata/influxdb-ruby,influxdata/influxdb-ruby,influxdb/influxdb-ruby,mvz/influxdb-ruby