Generated code is not formatted with nightly compiler

### Version

pascal@pascal-G533QM ~/L/D/q/c/quickwit-proto (conf_sort)> cargo tree | grep tonic
└── tonic v0.5.2
└── tonic-build v0.5.2

### Platform

Linux pascal-G533QM 5.12.0-051200-generic #202104252130 SMP Sun Apr 25 21:33:13 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

### Description

In our project quickwit https://github.com/quickwit-inc/quickwit, the code is not formatted or formatted differently when I run the build_script https://github.com/quickwit-inc/quickwit/blob/main/quickwit-proto/build.rs.

`cd quickwit-proto;cargo build`

These are the generated files on my machine:
[cluster.txt](https://github.com/hyperium/tonic/files/7734471/cluster.txt)
[quickwit.txt](https://github.com/hyperium/tonic/files/7734472/quickwit.txt)