v3.16.0

## Fixes

- Fix PIA port forwarding (#427) and remove the TLS x509 ignore CN instruction
- Add more Surfshark servers 
    - Add servers missing from surfshark zip file
    - Re-add multihop servers (see #424)
    - Fix logic to try resolving old vpn servers for Surfshark
- Change PIA settings more closely to their official configuration
- Restrict route listing to IPv4 only (#419)
- More resilient updater DNS resolution retry mechanism
- Use `8.8.8.8` as the CLI updater DNS server as `1.1.1.1` would not do some of the resolutions

## Features

- Hide My Ass VPN provider (#401)
- PrivateVPN support (#393)
- FastestVPN support (#383)
- Custom openvpn configuration file (#402)
- Uplift the 'localSubnet' concept to cover all local ethernet interfaces (#413)

## Maintenance

- Upgrade logging library (shorter lines, less external dependencies)
- Upgrade Go from 1.15 to 1.16
- Build Docker images for all CPU architectures on branches
- Use native Go HTTP client for updater
- Upgrade gomock from 1.4.4 to 1.5.0 (#394)
- Sort providers alphabetically in code
- Simplify environment variables comments in Dockerfile
- Return deduplicated choices from server filter options
- Upgrade golangci-lint to 1.37.0

## Documentation

- Update `New provider` issue template