VaultConfig is failing to normalise address when loading from environment

[rtib]

When setting up an address having a trailing slash (/), the driver will work fine since VaultConfig#address will normalise the address. Providing the same address via environment variable VAULT_ADDR and let the driver load it, the VaultConfig#build method is bypassing the address normalisation, ending up in a broken config.

[juggernaut0]

Just got bit by this, would be nice to have consistent behaviour.