libp2p-mdns 0.25.0

Implementation of the libp2p mDNS discovery method
Documentation
# 0.25.0 [2020-11-25]

- Update `libp2p-swarm` and `libp2p-core`.

# 0.24.0 [2020-11-09]

- Update dependencies.

# 0.23.0 [2020-10-16]

- Update `libp2p-swarm` and `libp2p-core`.

- Double receive buffer to 4KiB. [PR 1779]https://github.com/libp2p/rust-libp2p/pull/1779/files.

# 0.22.0 [2020-09-09]

- Update `libp2p-swarm` and `libp2p-core`.

# 0.21.0 [2020-08-18]

- Bump `libp2p-core` and `libp2p-swarm` dependencies.

- Allow libp2p-mdns to use either async-std or tokio to drive required UDP
  socket ([PR 1699]https://github.com/libp2p/rust-libp2p/pull/1699).

# 0.20.0 [2020-07-01]

- Updated dependencies.

# 0.19.2 [2020-06-22]

- Updated dependencies.