Fix: Parse url with encoded hash in password

[ftes]

Actual

# config.exs
config :my_app, MyApp.EventStore,
  url: "postgres://username:password%23with_hash@localhost/database"

Error: path should be a database name

Expected

No error, connects to database with decoded password password#with_hash.

Details

URI was decoded twice: parser.ex:42 and parser.ex:71

[ftes]

The docs for URI.decode/1 give this example:

iex> URI.decode("https%3A%2F%2Felixir-lang.org")
"https://elixir-lang.org"

Was that the purpose of this invocation?
The eventstore docs and tests don't mention that an encoded DATABASE_URL is supported, though.

As a reference, Ecto.Repo also does not seem to support that.